If you mean why hasn't the Luchese's whacked Paulie yet: Paulie never saw freedom after being imprisoned because of Hill's testimony.

Or if they havn't whacked Hill yet: Hill went into the witness protection program after testifying. It wouldn't be the easiest job to get a hit on him. He isn't in it now and this is 20 or so years on. Most of his enemies are now dead. Is it worth the successors trouble to kill him? Obviously no because he still roams the earth, although he does avoid NY.