On the face of it, this is possible because the remaster is built upon the original. It may have been given a graphical face lift, the insides are still mostly the same. It’s still very amazing in its own way. This means that gamers who are still playing the 21-year old game can instantly import their progress to the remaster when it releases this year.
Adding this to the fact that cross-saves will be a thing for Diablo 2: Resurrected, and you can basically play the game on the go when it comes out. Still no word on cross-play though. The remaster is set to be released sometime this year, for PC, Nintendo Switch, PS4, PS5 and Xbox Series X.