What would Vito have done? If...
Vito was invulnerable having beefed up his security after “his decision not to accept Sol's deal†and Sollozzo couldn't get to Vito
Michael had gone back to college
Fredo was well Fredo....
Connie in her abusive marriage with Carlo and Vito's inaction to Connie's plight
Sonny, Don in training, gets killed same scenario
I doubt Vito would have "uprooted" Michael.
First of all, in this scenario, Vito hasn't been shot, so he presumably would have more energy to continue to function as Don, and his enemies would have been less likely to view him as "slippin'."
Like Michael, Vito's long-term plan for the Family was legitimacy ("Senator Corleone...Governor Corleone"). He would not have abandoned his life's work by bringing Michael back for anything but the most dire of situations. I don't think that Sonny's assassination would have qualified, especially if Vito were still healthy.
Also, don't forget that Michael was pretty determined to go his own way until the shooting/hospital incident. Without those, I don't see him allowing himself to be uprooted by Vito. The more Vito would have tried to pull Michael in, the more Michael would have resisted. Ultimately, Vito couldn't have forced Michael to become his apprentice.
While it may be true, as Vito says in the novel, that "every man has but one destiny," and Michael's may well have been to become Don, I don't see it happening at that point under that scenario
