Such statistics don't get much more accurate than those you can see on Wikipedia. And assuming that the rate of growth of a language will remain constant is incorrect: what such statistics tell you is only whether a language once was or currently is a world language but do not allow you to predict which one will be next. Whether a language becomes a world language depends on many political, economic and social factors.
For example: if someone asked your question in the 15th century, they would have guessed Spanish, Portugese, Chinese or Arabic as the coming world language, but never English - yet what followed was the British Empire.
History of "World languages"
Hence I suggest you start by reading some history books instead to determine what factors are relevant. (Since the question "how does something become a world language?" has much in common with "how do empires arise?", "Guns, Germs and Steel" should prove relevant). You will note some things like e.g.:
- Latin was spoken in the provinces of the Roman Empire, but had not much currency beyond what Rome controlled by military or influenced economically.
- Languages change over time in different directions, hence over the centuries the Latin of Rome became the Romance Languages (yet only when the orthography of Latin was standardized did people start to realize that they speak a different language). Similarly, Chinese is a collection of languages (or dialects, depending on whom you ask) held together by the writing system. First traces of this you can also see with English (ever tried to call a support hotline outsourced to India?).
- German lost its status of "language of science" to English as consequence of World War 2 (there always are and were publications in other languages, though e.g. Americans usually ignored publications in Russian not just during the cold war but also before and after).
- Latin lost its status as "the language of Christianity" to the vernaculars in a development starting with the reformation and ending with the Second Vatican Council.
- French replaced Latin as language of diplomacy in Europe when France was powerful. With the rise of the British Empire, English became more prominent. With the dissolution of the British Empire after World War 2, British English was replaced by American English - an apparent continuity of language only because American English had not yet enough time to diverge from British English, hence the differences are not as readily apparent as it were between French and Latin.
- The European language has the languages of all its members as official languages and English, German and French as working languages: if the UK exits the EU then English may or may not be dropped, but the relations of Germany and France are such that both German and French will for the foreseeable future both remain working languages: so multi-language environments (driven by the concerns of the speakers of each language) do occur.
Factors determining the coming "World language"
From this one can conclude that a language becoming and remaining a world language is mainly characterized by the power of their speaker community, either military (enforcing their language over conquered lands) or economically (if you're everyone's primary trading partner then you can demand them to speak your language). How many people learn a language is only their bet on the prominence of the language (effectively a kind of stock market where people invest in languages they think might become important), but not actually the cause of the language's significance: after all, you want to predict the future world language, not the current one. Instead, one could look e.g. at the following parameters (though as mentioned you should read some history and determine which parameter was relevant in what way):
- Military power: while economic colonialism has mostly replaced military colonialism, military spending still determines how well one can support their position with violence (e.g. "speak my language") or at least how easily they might get wiped out of the race for world language.
- Currently, the United States still spend far more on military than the rest of the world combined, yet China is catching up (and India, too, though with an even larger gap).
- Russian military spending is aimed at recapturing its old empire in eastern Europe, hence not geared particularly at being a world language (though whoever Russia is not at war with has better chances to become world language).
- The military of Saudi Arabia will not be a strong boost to Arabic since once the oil runs out they can neither buy more weapons nor fuel their old ones.
- France, Germany, Italy etc. are members of the NATO which mainly operates in English (though techincally French is also official language). Even if the USA were to suffer a significant collapse, none of them on their own is strong enough to create their own empire and force their own language on it - even if they did it together, it would most likely be the same pattern of languages as in the European Union.
- Japan and South Korea military spending is because they are very scared of North Korea and China, not because they would be interested in an empire.
- Economic power:
- While the European Union is economically significant, it can be neglected for the purposes of a world language since it has not a single language but many of them, and at least German and French are in a deadlock with each other, neither willing to force their own language on the other nor to give up the status of their own.
- The United States are still economically significant and might continue for some time (whether their economic system is sufficiently sustainable or not is a discussion for another StackExchange).
- China's economic strength is slowly surpassing that of the United States, still is growing quite quickly and also has much growth potential. Consider, for example, that China is investing much in Africa to get the raw materials it needs to produce the goods it sells to the West. I think (but do not know) they are likely still speaking English (and French) there, but this is bound to change.
- India is still far behind: in principle it has potential like China, but has not (yet) been as successful in using it.
- South America is not just not very strong economically, they also have little leverage to improve: all they produce (bananas, coffee, oil, ores, ...) you can get elsewhere (e.g. Africa, Russia, Southeast Asia).
- Religion is (like language) usually not a factor of itself (spread by military means is more likely), but let's still look at it:
- Christianity has a lower population growth (both in term of natives and in terms of converts) than Islam. But the native population growth decreases faster in muslims (native population growth being mostly determined by availability of contraceptives). However, the effect from the rate of conversion is rather minuscle compared to other factors (like economics).
- Other religions do not have conversion rates anywhere close to that. Natural growth of population is indicative of nothing (except availability of contraceptives) - this goes not just for religion, but also for language (since children born into an environment take on the traditions of that environment, both religion and language).
- The number of speakers does not matter, since as already mentioned it is a trace of languages that once were significant, but no indicator of how significant they are going to be:
- Chinese is mostly restricted to China, and (the growth of) the number of speakers alone gives no indication how much potential remains (and how much of it actually is outside rather than inside China).
- The number of English speakers is because it is the current world language (technically the current and the one before: first the British Empire, now the USA).
- The number of Spanish speakers is because it was a former world language (when Spain had its own empire - the same applies to France, though in a smaller degree).
- Hindi, like Chinese, is mostly restricted to the Indian subcontinent since India was never a colonializing power but rather the victim of it (and thus speaking rather English than Hindi in outside interactions).
- The number of Arabic speakers is due to Islamic conquest. This was a phase which began at the beginning of Islam and pretty much ended with the dissolution of the Osmanic Empire after World War 1. Since then, expansion of Islam is mainly through conversion and immigration, yet this fails to spread Arabic as language, for while it still is the language of the Quran, people usually keep or adopt the language of the country they live in.
Now in the case of a war between the USA and Russia I would be quite confident that (if we aren't all blown to nuclear dust) China will fill the military and economic vacuum and thus Chinese become the next world language. A sufficiently severe economic crisis might also effect this, but more likely it will be a process that takes a few centuries - enough for others to improve enough to pose a challenge to China. Most likely this would be India - though they might just continue speaking English with foreigners rather than demanding Hindi.
However, it has been suggested (can't find source) that with improvements in machine translation a common language will cease to be necessary: one can simply write (or speak) in their own language, and the others will be able to read (or hear) it in their own language. Hence the most likely scenario is that English over the next few centuries will cease to be the world language, but be replaced by nothing.
Besides, I'd point out that the mental associations are not the thing itself: just because everyone loves their mother doesn't make the word "mother" a beautiful word. Similarly, just because they do not agree with American politics doesn't mean that there is any problem with English: indeed, a characteristic of a world language is that for most people the association between the language and the politics of the original speakers of the language is broken. I'm just guessing that they're taking issue with American politics rather than the English language itself, for as I noted most people cannot tell the difference between a word and its meaning.
Of course, there are many features of English that one might find less than appealing. For example, English pronunciation is notoriously complicated ("spelling bees" are a concept alien to most other languages where not imported from American culture). In fact, even though English uses an alphabet it should be more properly called a logography (similarly to Chinese). But this is no hindrance to a world language, but rather a shared feature: pronunciations differ (consider that foreign speakers have always difficulties getting the accent "right"), but the writing is the same (consider that foreign speakers tend to have better orthography than native speakers).