Right, so if you know this, why are you claiming that the removal of single-player will have any sort of influence on the state of hacks in the game?Diablo 2 was hacked to death because everything ran client side. It was easy. There was little Blizzard could do due to the architecture of the game.
EDIT: Actually, that's not even accurate; it's not relevant to the proliferation of bots or duping, which are the two most significant hacks on battle.net.