I don't think they will be giving up on Symbian quite hyet. They may not release much in the way of new features, but for now it's still selling well: http://phandroid.com/2011/02/09/gart...-in-the-world/
Sure, it's "losing matketshare" to android... But they shipped 110m phones, up from 88m!

Meego -will- happen on a few devices, whether or not Nokia participates - Intel has the budget to play with it for a while.
Nokia -should- stick with it, simply because Intel's got a part of it and won't let it fail -- at least, not for a while.
The fact that Quim's not worried makes me think this is the case.

As far as QT on Windows... It already works fine on Desktop windows and should continue to.

If Microsoft allows it on WP7 as a toolkit... It could help out Microsoft and Nokia at the same time as someone can write the same basic application for yet another platform.