There's very little doubt NOKIA would have phased out Symbian and replaced it with some Linux based alternative(s) but once Qt was running right across all NOKIA's devices who would've noticed and who would've cared? Carriers would have continued marketing NOKIA phones, users would have carried on buying them and developers would have carried on developing for them. There would have been no 'burning platforms', no huge disruption, no induced collapse, no dumbing-down/locking-down of devices and no association with a toxic third party. On top of that NOKIA would have retained control of their own ecosystem and all revenue from it.