quality over quantity. veterans haven't been updated in forever, so I'd like to see them be brought up to par with newcomers.
they can't go beyond Ultimate, character-wise. I
don't want them to go beyond Ultimate anyway, because it's apparent how existing characters are neglected in favor of newcomers, when a lot of Nintendo's most enticing characters are already on the roster but don't feel like themselves. If there was ever a time to "hit the reset button", it's now. People who enjoy the old movesets can stick with Ultimate since that has all the characters; I think that revamping a lot of veterans is the correct course of action, then continue building up from there. add new mechanics on top like meters/assists/aerial smashes/etc (basically changes to the core gameplay formula that can evolve the platform fighting in a bold new direction), and I'll be set.
The next game is going to have cuts. There's no way around it. And if we're gonna have cuts, I don't want to go baby steps where there's around 60 characters and most of the veterans are still untouched; no no, I would personally go full-on scorched earth and get my hands bloody. nuke everything, start from ground zero. A wise man once said, "if the importance of Yoshi isn't being called into question ya haven't gone far enough".
the next game cannot be essentially "Ultimate with less content". it has to be something new to entice people, because Ultimate can't be topped character-wise. I am totally and completely fine with Smash in its current state ending at Ultimate, since sooner or later something's gonna have to change, and Ultimate is the perfect swan song for this "classic" era of the series.