While Diablo 2: Resurrected launch date isn't due for some time, we've got a good idea about how the game will look thanks to some gameplay footage that emerged some time ago. Developer Vicarious Visions had to build Diablo 2: Resurrected from scratch due to Diablo 2's source code being 'lost'. Therefore, it would be reasonable to assume that anything from the original version would work with the refresh.
However, that doesn't seem to be the case, according to the game's producer Matthew Cederquis, who told IGN Middle East in an interview that the original Diablo 2 save files will work with Diablo 2: Resurrected. It also (indirectly) tells us that there will be no new gameplay mechanics added to the game, which is a little disappointing. Although we don't quite know how one goes about importing said save files, that information should surface once the game is close to release.
This should come as good news to Diablo 2 veterans who put in countless hours to max out their characters. The nearly twenty-one-year-old game still has a (somewhat) active community that will welcome the addition with open arms. Grinding for items in Diablo 2 can be a bit frustrating due to the abysmally low drop rates.