Also keep in mind if it is a "Switch 2 Edition", the later it shows up, the less sense that makes, because it'd just close the gap between when a better selling original game could be ready.
I mean presumably the plan on the og Switch was to eventually have a new, original Mario Kart, and the port showed up in month two.
I would surmise that it seems unlikely we would receive a Switch 2 Edition of Ultimate in 2025, otherwise it probably would've been shown with the others. And if it came in 2026, but a Smash 6 could otherwise be ready in 2027... would they really make a Switch 2 Edition?
Smash, unlike the games that received Switch 2 Editions, generally becomes a platform for sustained multi-year content - sort of like Splatoon and probably Animal Crossing - two other games which didn't receive Switch 2 Editions.
The games that did get Switch 2 Editions don't preclude DLC, but they aren't ongoing services.
So the existence of a Switch 2 Edition Ultimate would either be to usurp the role of an actual new, better-selling Smash, even though one could probably be ready shortly after it, or to just exist, briefly, before being replaced, which renders it... superfluous.