I'm not aware of any new games which compete in the few areas in which AO excels. If the AO team succeed in developing a system of relationships between class capabilities which provides more fun and interesting play than that developed by the crack-monkeys of the past, then people will stick around to experience this. You can't doubt that lots of people will return at least to see what they think of the rebalanced game. If there's a lot of new things that they like, some will stick around.
It all comes down to whether or not the game is generally more fun post-rebalance. If it is, the population will probably rise, regardless of any competition.
