100% says we log into the same account for all blizzard games. thats what makes realID work and that is why wow switched to Battle.net instead of its own login like it used to be. As for SC2 being a subscription game, i don't see that happening. Once that game is released, they can leave it alone and give it updates periodically, but all the games being run off of Peoples Machines and not Blizz's Servers means releasing to game to the public has no upkeep for blizz to take care of. all they have to worry about is Glitches and Errors in the code.