The auction houses in the PC version of Diablo III may be going away, but Blizzard insists that the game will still require an online connection, and that policy isn't changing.
The studio informed Rock, Paper, Shotgun when asked about its online policy, "We do not have plans to implement an offline mode. While the always-online requirement made the auction house possible, the auction house was never the driving factor in our decision to make the PC version of Diablo III require an Internet connection. The game was built from the ground up to take full advantage of Battle.net, which provides a number of important benefits, including persistent server-side character saves, a seamless PC multiplayer experience, cheat prevention, and Real ID and BattleTag social features.”
The console versions of Diablo III, which were released this month, do not require the player to be online to play.