For a Toronto move to happen, the following all needs to happen:
(1) A Toronto ownership group has to outbid any ownership group in Buffalo or anywhere else, and be able to pay the relocation fee that the NFL charges teams moving to larger markets (they have to compensate the loss of a potential expansion location ---- the NFL might waive this to some extent but it's still an issue). (moderate difficulty)
(2) The NFL has to be okay with destroying the CFL, which will happen if there is a full fledged team in Toronto and defending against the inevitable lawsuits if such a move occurred. (high difficultly).
(3) Either public authorities or the new ownership group will have to pay for a state-of-the-art stadium to replace the Rogers Centre, because it is not a NFL-class stadium and sustained revenue growth requires a higher class of stadium. (moderate difficulty)
I am not saying that the Bills are not at risk of moving, but I don't see what makes Toronto so inevitable.