re: If Sonny Corleone doesn't get whacked, does the Corleone family win the war?

What a lot of people tend to overlook is that Sonny, hothead though he might have been in personal matters, had been groomed to take over the Family from a young age. It's perfectly possible to be a hothead in one's private life and a professional when dealing with business. There's no reason to believe Sonny would have ignored the input from both his father and his capos. Even Tom could have been a helpful influence because it was Michael who decided Tom needed to be sidelined because he wasn't a wartime consigliere. Sonny might very well have kept him on.

The nature of the war changed with Sonny's death. Vito moved for peace to help save Michael's life, not necessarily because they were losing the war. It can even be posited that the loss of Sonny was a tactical blow that influenced Vito's decision over and above the personal one.

Edit because spell check decided consigliere simply HAD to be "configured" no matter how many times I changed it back.