I think it would depend on a number of factors.
For one, it would have to be made by passionate-enough fans that want to see it to the end. If it's not then it won't get finished. Look at the dozens of Sonic fangames that get cancelled after they release a one-level-long demo.
Second, it can't make money or else it gets taken down. Sega is generous enough to leave up Patreon pages with optional donations, but Nintendo isn't as generous. So no money, donations or not, can be made off of this.
Third, it needs to be able to work after updates of the game are downloaded. So if a new DLC character comes out and I download them while I have a PM style mod on my Switch, the PM style mod should still work. If this can't happen we would have to wait until the game stops getting updates-which would at least be two full years from now.
Fourth and finally, let's make sure it doesn't take over all tournaments. Until Ultimate becomes forgotten by Nintendo, we should keep it as a side event, because the more traction it gains, the more Nintendo would want to take it down.
There's a lot more that would need to happen obviously. But if the stars align, we could see a Project Ultimate of sorts come to fruition. I wouldn't use it since I've become so accustomed to vanilla Ultimate and the imperfections like the buffer system don't bother me as much as others. But I would be happy for people who really want it and may even try it out myself.
