I don't think they will require 280+ AAs to level when CoE comes out. You don't really need that many AAs to play, most of them are fluff that give marginal incremental improvements anyway. The 280 requirement for Skyshrine was probably there to create an incentive to play the game more than any actual need to have so many AA. Remember that there are two overland zones, and those typically are created for casual players. So, if there is 95 casual content it follows that you won't need 280+ AA to be able to play there. That would be pretty stupid if they did that. AA requirements will still be in place to get the higher level AAs though (such as prestige). It could be used as a gatekeeper for higher level dungeons but even then it is not really necessary to do that.