at this point, given western 5.4 timing (no idea on china's 5.4 timing), would say around 250-500k loss.
q4, of course, I would expect to be worse than q3, whatever it ends up being.
I do think that unless blizzard finds a way to get out of this McContent quick-bites content quick-consumption design philosophy, they are going to have a hard time keeping folks engaged in any expansion after initial spike. For the record, I am not at all sure they CAN get out of McContent-type design. The crowd is used to it now. Pandora's box is open, but I just don't see how having almost anyone who cares to try beat the big baddie on the patch splash screen within a few weeks of release (and that only gated by LFR gating) works as a viable content longevity model.
I know, I know, 'but did you beat it on heroic?' I suspect many players roll their eyes as much as I do when I read that question. Did I beat d2 on hell difficulty? well no, but I saw the diablo and baal fights enough to be satisfied that I did see the game, just not on the extra-super-hard setting.