I think Nokia can sell any OS.
Think about it while Nokia was selling tens of millions of s60 devices, samsung mobile and SE was dropped to almost non existent making a loss putting out failure after failure trying to sell symbian s60/uiq.
Towards the End Samsung and SE was putting out S60 devices with miles better specs but still lost to Nokias average spec'd devices like N96 & N97.
Which makes me think its only the Brand Nokia what as kept Symbian alive these past few years b/c people want a Nokia device.
I don't think a different OS will change anything for 90% of Current Nokia consumers they will just follow suite quietly, but it could open the mind of People at the highend who have never touched Nokia based on the hate they hear surrounding Symbian.
Lets just hope it's MeeGo on future devices that the millions go crazy for and not anything else