Well written, but I don't think your concerns are quite in the right place. The way I'm looking at the evolution of the platform, Maemo 5 (while not at the 'end of the road'), is looking increasingly polished and ready for everyday use.

The much bigger interest in the N900 vs any of the prior devices (c.f. Google trends, etc) is also a good indicator that the 'splash' this makes will be a lot bigger and longer lasting, possibly attracting some real clout to third party application development.

Of course, yes, Harmattan is still down the road, but really, this is the way technology is as we know it - new stuff obsoletes old at a rather breathtaking pace, even in more mature markets like desktop PC land. (Mostly on a hardware level now, the maturation of the software stacks there happened a few decades ago - yet people managed to use them in business situations, regardless of the (lack of) stability). [edit: and yes, the encouragement of Qt applications in Fremantle will make the transition to Harmattan a lot less painful, I think]

In what way, really, are you concerned about Maemo 5 as a development platform being an issue? That would be my real question to come out of this. If you're concerned about it as a development platform, then you might have some merit - but as an end user, I think you're likely to get quite a good experience.