If Geno is in, we have the full 4 "these are impossible for Smash" since Brawl complete (Ridley, King K. Rool, Banjo & Kazooie, Geno) and I think that would be an accomplishment for the fandom. Which character would be next?
Issac, Lloyd, Rayman, Waluigi, and Sora are the big five in my eyes that have had fanbases since Brawl that have kept morale going. I'm pretty confident that we're going to get at least two of these guys by the time Ultimate is done. This year has been very interesting for all of these characters:
-Major Golden Sun copyrights were updated not only in 2018 but 2019 as well. If it's not Smash, I think there's enough to consider that Nintendo is going to do "something" with the property probably within the next year.
-Rayman recently had a major copyright update akin to what Banjo got in October 2018 and Takes in September 2019.
-Tales had a big copyright update last year and Namco has even said big announcements for the 25th anniversary are coming at some point this year.
-I know people get on edge when Sora gets brought up here but, damn son, Disney and Square are HARD pushing it this year. Several announcements already with more to come, multiple mobile games, and a full blown animated series coming to Disney+. This is aggressive marketing like the series has never had. I'll say it again... I think both Geno and Sora can make and, based on everything I've heard, Geno would be early while Sora would be late in Season 2. Geno's very likely to be 7 or 8 while Sora would probably be 10 or 11 if he wound up with a full pack. As I've said before, him and Rayman are currently the only third party characters I'm really entertaining right now for potential "bonus content" based on a growing number of factors. I know it's been like the Palestinian conflict at times this past decade and a half but Ultimate may wind up being the game where Geno fans and Sora fans can finally make peace with one another.
-Waluigi is Waluigi. He's basically the new Ridley who was the new Cloud who was the new Megaman who was the new Sonic who was the new Pit.
Time will tell but I think the future holds a lot of good things for these ever green characters, even if it doesn't wind up being Smash.