So, wait, is the 24th here still the release date?
I ended up re-buying Diablo 3 myself (my previous account had been annihilated by derpage awhile back) after hearing about all of the changes/improvements, and.... yeah. They got a good thing going here. The game's popularity is rising waaaayyyyyy faster than I thought it would. I'd indeed say there's a definite chance of another "Diablo blasts your sales" sort of situation here.
I know I'll be getting that expansion, though in my case it wont affect the purchases of anything else.