I wonder
If Tony hadn't butted in, what would have happened? I believe Ice would have probably won the fight but doubt if that would have finished the feud. Tony would have had to.fight Bernardo sooner or later.
After the end of the film- I expect they'd have cooled it and the gangs would have gradually broken up. They were coming up for draft age. Maria and Anita would have presumably eventually "found another" from "their own kind."