From what I understand is it is still D2 and all its glory. Though it will have the option to toggle on and off the new 3D overlay, along with some quality of life changes.
I also heard they will be bringing it to the Xbox and PlayStation, which will be interesting to see.
D2 is by far the best game in the series so far and as much as I love D3 it has been a big let down. As annoying as it was I wish they had kept it in it vanilla state.
Here is hoping that D4 lives up to the hype I have built up for it, as a lot of the core mechanics are coming from D2.
Will definitely pick this remaster up regardless for the nostalgia at least.