I think it would be very wise for wow to release an expansion that has nothing to do with game progression. By that i mean an expansion with new races, numerous aesthetic options. and so forth. this could be removed from the linear expansion model (i.e. could be purchased and function with only classic wow) and would not improve gameplay for buyers. this would be similar to in-game store purchases, but just a broader package of things (races that are unobtainable otherwise would be the big seller). I, for one, would buy it.