Well Meego/Maemo6/Harmatten having Flash 10.1 is pretty much a certainty. If Nokia doesn't provide an official update for the n900, I suspect the libflashplayer.so could be copied onto the n900 from the Meego image, given that it's the same build and hardware target. It's also quite possible that Adobe could distribute the library via the OVI store, since it's really in their interest to have compatibility among as many devices as possible. So even if Nokia were to issue an announcement that Flash 10.1 isn't being offered for the n900, it wouldn't be the proverbial nail-in-the-coffin.

I'll also say that we're not just dealing with HTML5 vs. Flash; Microsoft is still really pushing Silverlight, and I'd hate to see that gain any more traction than it has.