My guess is no more than 3 total. It will likely be similar to SC2, having 3 per game.
WoW is blizzards way of massive income, so of course they drag it out.
I haven't heard anything but knowing Blizzard have been dragging World of Warcraft with countless expansions since the release for almost 10 years now I won't be surprised if they did release more Diablo III expansions.
My guess is no more than 3 total. It will likely be similar to SC2, having 3 per game.
WoW is blizzards way of massive income, so of course they drag it out.