I guess they could do direct sequel involving Jennifer Connolly (her grandchild is kidnapped), new actor playing the Bowie role (same character)
Or a new unrelated sequel - random kid taken, new goblin king, but a lot of the same characters reappear (Hoggle, Didymous) with a lot of same story beats, calbacks and easter eggs, so like 80% of legacy sequels really just a remake of the original film