For this question, prior to today, the answer was 'we don't know'. So I answered as such when the question was asked. Now that we know, how to proceed? Should we:
Stack Exchange has wiki-like features specifically to handle the case where an answer is longer relevant or true and can be updated with new information:
Stack Exchange was specifically designed to adapt well to rapidly-changing events. That's why it has Wiki features. Like Wikipedia, we are not content to wait for the first historians to write the book. We're happy to answer questions in the context of what is true today, knowing that as facts change, the answers can easily be edited or replaced.
Simply edit the answer (or, if you don't have enough reputation to do so, suggest an edit) with the correct, up-to-date information.
Comments are ephemeral and are meant to help clarify and improve the answer: you can ignore them if they no longer do that. I'd go one step further and flag the answer for comments cleanup by a moderator.
Business as usual: if there's a new tidbit of information, edit an existing answer. If a lot of new information is revealed, post a new answer.
If an answer becomes incorrect and is no longer interesting (for example the answer says “we don't know”, but we know everything now), downvote it.
Such time-sensitive questions should have a community wiki, ideally accepted answer, containing all known information with references.
Although everyone can edit answers, CW makes sense here, because it conveys the message that the reference answer is supposed to be edited by anyone.
There can be other (non-CW) answers, containing speculation. (Not just one-liner non-answers, but actual interesting inferences with citations to back them up.)
