Everything I've read (and this is much hearsay, considering Nokia never released information about the N9) leads me to believe that Maemo6 will be a slightly repackaged Maemo5, and definitely will not be Meego-compatible.

Now, Microsoft would certainly love it if Nokia were to market Maemo6 as a "kind of Meego", since that would destroy Meego's credibility and greatly damage Linux mindshare.

But I don't think it will ever happen, not even Microsoft is that evil.