4. There is no MeeGo device out there, in fact even the core reference platform for it does not exist.
And Nokia openly claims that you should get N900 if you wish to jump on the MeeGo train. That says two things - they indeed value the N900, and that N900 will be at core level compatible with MeeGo even if it doesn't get he MeeGo itself. 5. For f. sake, you've purchased an open-source(ish) device so that you don't hold all your eggs in one basket, namely so that Nokia is NOT the one and only in charge of what will become of your device, now practice that privilege!
N900 is out there and it is NOW, what the future will hold for it and how the things will develop we cannot know, I don't think that even Nokia themselves have a very clear idea on that one. If you keep looking in the future ignoring the present you will never get a new device, as the next one wil probably be better, faster, with broader support... that's the nature of technical progress.
Painstakingly typed on my N900