Huddleston and Pullum (2002: 209-210) address this matter directly. They argue that, contrary to what one finds in traditional grammars, there are only two tenses in English, past and present/future. Crucially, the modal verb will should not be construed as a marker of future tense, but rather it is a marker of modality. They even state that will can denote past occurrences when used together with perfect aspect. The example they give is next:
(1) He will have left already.
This sentence denotes a past occurrence, and in this regard, it aligns with the sentence in the question, i.e. You will have seen the news, which also denotes a past occurrence (with present relevance). The past occurrence is epistemically flavored, though, that is, it is not as certain as the corresponding simple past tense version of the sentences, i.e. He left already, You saw the news.
German has an analogous construction with the modal verb werden 'will', e.g.
(2) Da wird sich seine Mutter gefreut haben. 'His mother will have been pleased.'
My Dudengrammatik (1984: 152) states that the tense in such cases is Futur II 'future perfect'. But it states that in this use, the Futur II actually has past time reference.
I therefore predict that grammars vary concerning the terminology they use to denote the construction. Some grammars likely state that the construction is indeed a manifestation of future perfect tense, but they then probably hedge the classification by stating that this use of the future perfect can also denote a past occurrence. Personally, I would favor Huddleston & Pullum's assessment of the construction, since their grammar is comprehensive and excellent in many ways.