Well if it was exactly the same then maybe I'd play it, but not as much as I'd usually do.
That being said, if WoW was truly a single player game then certain aspects of the game would just work diffrerently. They would for example put a lot more emphasis on questing and make it more fun/interesting like it is the case in other RPG games.
IMO WoW is overall fine the way as it is right now, where a whole bunch of the game is single player already and all you really do is meet people in the world and have a choice to play with them, whereas the actual group content is separated and more reserved for end game.