You can import Diablo 2 save files into Diablo 2: Resurrected on PC, Blizzard has confirmed.
Speaking to IGN, Diablo 2: Resurrected producer Matthew Cederquist said: "Yes! Keep your old save files.
"Back when we were working on [the remaster], we wondered if the old save files would work, so we kind of shoved it in, and it worked! So yes, your local single-player save files will carry over.