It could be, and it would be in Blizzard's interest for it to be. Seems a little soon to me but the game isn't bringing anything newer (lastgen graphics) than the infrastructure they are using for web support in it.
Either way though, real money auction house that blizzard will be skimming a percentage off of? That company can go blow elephants, nickel a herd.
It's false - Game Retailers need to share a release date to help create buyers. It's a sales technique and every retailer does it eventually. I pre-ordered Starcraft 2 in April of 2010, where GameStop had told me they will have the physical copies by June. Release date was July 27th. Diablo is still in Closed Beta, I'm going to guess that it's going to be another 2-4 months before they actually tell us the direct date of launch. Still a load of bugs to work out.