Probably a hot take, but if we do get another Wario Land or World game, I hope they leave Waluigi out of it. The Wario games are so distinct from the Mario universe that they feel like there own separate thing.
Waluigi always felt more like a Mario character than a Wario one and it would feel lazy to just add him in now.
Just played the demo for the WarioWare inspired game, Buster Jam, and WOW! that game was dope! The dev team definitely made the right choice going that direction. It's way more fun than their original intended game.
It's surreal how many indie games Wario has inspired.