They can win!
Clemenza and Tessio's crew were full strength, Rocco's secret regime even if it was not up to the desired level at that time, it is still extra, in addition to their existing muscle
I believe there is a lot the Corleones can do to "stop or counter" and win the Gangland war against even combined Barzini and all the other families
- Barzini outed himself as the puppeteer in this Sollozzo business and Sonny's murder, at their Commission meeting – not a smart move!
- Cuneo and Strachi small potatoes
Obviously the “outright war” throws a spanner in the works regarding the Baptism massacre because the surprise element is lost and the Corleones' acting weak / weaker cover is blown
I might add, I can't see the Corleones asking the Molinari Family [or any other friends] for help
The Corleone pride, like they can't fight their own battles / war
