A D2 HD can be cranked out pretty quick, and there was an ad out in late 2015 advertising for developers for "legacy games" so something may be in the works. The advantage of doing D2 HD is mostly very little development effort.Quote from Rotterdam
You also have "Lost Eternal" coming out.
A D2 remake woudnt sell big. It only attracts the old school players who played Diablo before.
Honestly even a remake would look like crap. The game is freaking old. Making a new game or an expansion of D3 would be so much better in general.
Better for the company and gamers.
D4 might be a possibility, but it is pretty far away timewise is my guess. D3 expansion seems pretty unlikely to me, given Blizzard's experience with D3 sales falling off a cliff from Vanilla to Reaper of Souls, and also their history with SC2 with each expansion selling less than the previous one.