I hope they add F.L.O.O.D. to the next 2d mario game.
That would problaby work well since the rocket and turbo nozzles basically moved mario in 2 dimensions anyways.
It could open up the level design to have more secret areas and difficult jumps(if they designed some later levels so that you replenishing the water tank wasn't always an option so you have to be careful not to waste water), plus I would like water cannon a bunch of hammer bros. guarding a secret area.