This is only speculation but if Neil hadn't succumbed to cancer, Gotti would be a dead man or at least part of the crew would have been.
I believe Neil was still alive when the drug charges first occurred. Neil was old school. The boss is the boss is the boss in his book. Gotti would have to kill him too.

Also, its speculation Neil would have survived the large scale indictments that went down. Was he any smarter than all the commission bosses? No I dont think so. He would have been caught up with the rest. Ravenite was bugged, no doubt Neil would have been implicated directly or indirectly by them.
As far as being boss. Its not desirable now, but back in the '70s and '80s the mob didn't see what effects the RICO statutes could have.