Would be nice if they added a new max race count every wave (+8 each time); the more options the better!
Speaking of options, I wonder if they'll revive any of the scrapped features found in the files of Deluxe. The unused Expert difficulty feels like the easiest one to add; doesn't even need to be applied to 200cc GPs, just have it as an option for VS Mode. Reverse Mode is a far taller ask though, and not one I expect. It was
scrapped from Double Dash, then revisited again for 8 Deluxe, and finally ended up being realised in Tour. Sure, that means the layouts already exist for the tracks being ported up from Tour (all of the DLC), but would they really leave out the vanilla tracks like that, or would they go through the effort of making reverse versions for all of them? Both outcomes feel unlikely to me.
Last bit of curious cut content from 8 Deluxe (again, none of this existed in the original Wii U release) is the Bomb Car from Double Dash and Wii; present on GCN Mushroom Bridge, GCN Mushroom City and Wii Moonview Highway. Maybe they planned on adding it to one of the battle maps? In any case, it may actually end up used now, as the object also exists within Tour (alongside the Wiggler and Mushroom cars also present on the former two GCN tracks), likely to be used in the future.