By the way. Battle.net WILL BE OPEN when the game comes out, the PvP "ARENAS" will come later on. So the co-op gameplay we are used to from Diablo 2's battle.net is still there. The new feature is simply being brought as a later on patch.
I have mixed feelings. The feeling of D2 has changed. co-op battling is still fun but too many has changed, it really takes some effort to get used to. Still, it is looking nice =)