They're also using this venue to host Hearthstone and HoTS Events - more here. I certainly don't think it's a dead game. Blizzard is smart and they've got a big marketing campaign ready to launch in line with Blizzcon. They want to give teams time to get their local marketing together, they want to make sure the Arena is packed from the beginning. Come season two we'll be seeing bigger venues in each city, let alone just LA.