You know, considering how Smash Bros. is still made by Sakurai to this day, as it would seem, I think this...
...Sakurai was also previously the developer of Kirby games, which were known for having different villains most of the time for each game. I know he does not work on Kirby anymore, but the Smash Bros. series has had different villains per game, too, including Tabuu, Galeem and Dharkon and if it counts, Master Core from Smash 4.
My point is that if Sakurai is still in charge, as long as he is in charge of Smash Bros. as a series, I think even if we wanted otherwise, I don't think Smash Bros. will really get a recurring villain. I know there are Master and Crazy Hand, but to me, they are important to the world of Smash Bros, have been controlled by the likes of the bad guys I have mentioned, and are more like how King Dedede is in the Kirby games nowadays to some extent than being actual true villains.