The problems with calling it something different, is the story continuity. Yes we learn in the opening Umbrella has been destroyed. But what about the facts. The people aren't human or zombies. Someone from RE history will be appearing. Many of the rumors focus on Wesker, and his mysterous, the stolen virus, and his employer. If the story fits into chronology, it would make no sense to change the title. It's not like Mario or FF where each title is independant.