Look at the demand for LAN in SC2, and that has FAR more use and also more pressure because the outcome of $100,000 tournaments are riding on it (disconnects etc). Blizzard never moved on it.
They're even less likely to on D3 because online is necessary for item consistency. They want the supply limited and cheating gone so that RMAH can work and your game experience means something (so you keep coming back).







