I’d also kind of like to see Happy Death Day 3 get into ‘80s R-rated action, but that may be wishful thinking given the PG-13 rating of the other two.
I suppose a self-aware rom-com could work given Tree’s history with Carter, although there have always been romantic elements threaded through these movies.
Beyond that, should a third film go into production, perhaps there is a way the franchise could then work a third genre into the potential sequel?