No, I don't believe in destiny anymore than I believe in the religious concept or predestination. I also don't believe in momentum except as a result. Destiny and momentum are results, not causal variables.

The novel and film illustrate the variables affecting Michael's path. Why did he murder Sollozzo? He stated so: it was to keep Sollozzo from murdering his father. If Vito had recovered from his wounds earlier than he did, he probably would have been able to preclude Sonny's murder. Having done that, he would have not had to incorporate Michael into his criminal empire. Thus, Michael would not have taken command of the Corleone empire. Under those circumstances, if Vito had worked his magic and eliminated any threat to Michael once Michael returned from Sicily, there's nothing to indicate that Michael would have been part of the Corleone empire.