Personally I REALLY want Infection back. Flood was a cool idea, but when it came to matchmaking/custom games I just didn’t feel the same love and admiration for the game mode as I had in previous halo titles.
They’ll probably do what they did in halo 2 anniversary. Have flood spartans with swords instead of meaty arms.
Since warzone is a simulation, there could and should be flood.
I say have both just for the sake of variety