A: While we do not know the answer to that for sure, if MS were making a change that large, we would know well in advance. While possible, we do not expect MS to do something to change the file extensions. We are 95% certain this will be a roll-up of all the Office 365 updates to date that the “perpetual” licenses missed out on. (With maybea user interface freshening). To perpetual license users, it may seem like a major upgrade (new features, etc.), but to 365 users who are getting constant updates anyway, it appears to seem like a normal update.