His spirit lives on through Legacies, in the Salvatore School itself (which was given to Caroline by Damon after Stefan’s death) and through Damon and Elena Gilbert-Salvatore’s daughter.
Paul Wesley has already joined the Legacies family to direct an episode of Season 1.
He seemed like he might up for the idea of returning to The Vampire Diaries and The Originals spinoff as a monster-of-the-week, but not to revive Stefan Salvatore.
Stefan’s story is over, as played by Wesley, anyway.