To get back on the rails, Nokia would have to completely distance itself from M$ and I don't think Steve (Monkeboy) Ballmer would be an easy thorn to pull.

M$ have allowed Nokia to continue with Symbian for another 12 months, hence their statement that they hope to sell another 15million Symbian units within that time. (Do that many people buy a new phone each day?) Then M$ will dig it's claws in and maybe they'll gradually go for a 100% take over.