DiabloFans

The thing to remember is that they don't want to turn players that spend over $200/year on subs and annualized xp boxes into someone that just buys a box. Let's say a player stops playing WoW when SC1 comes out, buys all 3 SC boxes through summer 2012 and buys D3. They will actually have lost money on that player relative to WoW subs, even with selling over $200 in boxes to them.

This isn't quite so much of a threat with a science-fiction RTS that doesn't really cross over with WoW in any meaningful way, but this is why we still may never see D3. If you had the most profitable product in entertainment, with insane profit margins, would you want to release its only potential killer?