I wonder whether it makes sense to consider the east Asian languages (Chinese, Japanese, Korean, Vietnamese, and potentially others) as part of a sprachbund, like the European languages in standard average European
The CJKV languages have a long history of contact and a great deal of shared vocabulary borrowed from classical Chinese, but there are many similarities that go beyond vocabulary (and cannot possibly be due to genetic relationship)
For example (just some features which come to mind):
Prominent use of classifiers (AKA counters, measure words)
An elaborate system of honorifics/politeness
At least partly Pro-drop
Use of Reduplication
simple tense structure; verbs that conjugate according to tense (if at all) but not subject. (Chinese formally has no tenses but sort of has a past tense via addition of -了)
Phonology: mostly CV syllable structure; few final consonants other than -n or -m. (And in general it seems speakers of CJKV don't have as strong of an accent when learning other CJKV languages versus foreigners from outside the region).
A system of single syllable grammatical particles.
Many affixes like the equivalents of pre-, post-, anti-, non-, -less, -ful, -ness, -ology, -ization, etc. are the same.
Use of the possessive to form adjectives from nouns. For example in both Chinese and Japanese, "great hero" would literally translate to "greatness's hero".
Head-final in noun phrases.
Allowing the use of third person to refer to oneself or one's audience. In formal cases, for example the utterance "I am here to serve your majesty" might be rendered as "the servant is here to serve the king". In informal and colloquial situations, there are many times when one uses third person (especially with a nickname) in place of "I" or "you". In English, especially when talking to children, we use phrases like "Daddy is here!" but this practice is far more common in Chinese or Japanese.
Rare use of third person pronouns. Japanese and Chinese have words for he/she (彼、彼女、他、她), but in practice those words are better translated as "that person" then he or she. They are usually only used to emphasize reference to a specific person whose name is unknown.
There are probably many other features which I didn't think of.
I think at least the first few points apply to all the CJKV languages, while the later few may only apply to CJ (the two I actually know). Please correct me if that's the case!
Has the existence (or lack of) of an East Asian sprachbund been discussed among linguists?
Edit/further comments: I specifically include only East Asian languages, that is, those historically influenced by Chinese, the only major ones being CJKV. For centuries all educated people in Japan, Korea, and Vietnam were proficient in Classical Chinese; the formal registers of their languages are all heavily influenced by classical Chinese, and at least some of it has trickled down to the everyday language (beyond vocabulary, which in each language is heavily Chinese based).
Essentially, I am wondering why there isn't an idea of a Chinese-influenced language region, much like how the European sprachbund (especially Romance languages+English) is a Latin-influenced region. There is a Wikipedia page on the languages of East Asia but that doesn't seem to correspond to any particular linguistic concept.