...Had Wario failed to stop Rudy? Before facing off against him, Rudy said he was going to conquer the outside world after the music box, so what do you predict it would've looked like or what would've transpired?
Since Wario is within Mario's extended universe the Mario Bros. will probably get him once he tries to take the Mushroom Kingdom. It would be like another Mario and Luigi game.
Seeing Rudy face off against the denizens of the Mushroom Kingdom would be really awesome! I wonder who would be the first to be made aware of his presence. Like 3rd Wario Brother said, Plot Armor: The Character would probably make short work of Rudy, but I'd love to see how other characters would fare against him, hero and villain alike? Taking it a step further, if he ended up conquering the Mushroom Kingdom, would he try to also take over the other dimensions hidden in it, like the Shake Dimension? I've often wondered how Rudy winning against Wario would play out.