No, it's not an "everybody wins" scenario. That's tempting but ultimately flawed thinking. More vets means less newcomers and/or less other content they could put that effort into. Everything has an associated cost. No matter what you do, you are forced to make choices about what gets put in and what gets left out. Sakurai has even talked about the realization that no matter how hard you try, someone is going to feel disappointment. It's fine if EiH is what you personally hope for, but it's misleading to portray it as a route with no downside.
I mean if the baseline expectation is a dozen newcomers or somewhere around there, then yeah most of the roster is gonna be vets. And I don't think anyone sees an issue with that really, as long as there is enough new stuff to be worth the price point, and to adequately reflect how the landscape has changed since the last roster was made. People still largely see Smash sequels as iterative in nature; I think going forward, they will generally be less "iterative" than Ult was on 4, but still more or less building on what's been established roster-wise.
We'll see what the future holds beyond this next game, but at least for now, tbh, I don't really see a lack of newcomers that are still easily justified additions even in the face of a swath of potential cuts. If we shave off a significant portion of the more likely-to-be-cut vets this time, it may possibly get harder going forward, but at least for now we're not really running into the issue of "skewed trades" IMO (and a lot can change btwn now and then besides).
On the Dixie for KRool point, I definitely don't expect that "replacement" either, but maybe you can squint and see it in the context of building Dixie off of Diddy and therefore fitting her in for less resources than it would take to remake KRool, and you still get an important and fan-demanded DK character out of it.
But yeah, overall, the mentality of direct replacements is quite flawed. I mean we have some precedent for it like with Lucas and Ness in Melee (albeit a niche and unlikely-to-be-repeated scenario), and it's clearly been shown to be possible for newcomers to outprioritize same-series veterans (which I do expect to reoccur), but on the whole they really haven't evidenced the desire to operate that way at all, nor do I think they really should operate in those terms.
A priority-based system necessarily invites comparisons between candidates on merit, but the flaw is that same-series characters don't encroach on each other's turfs nearly as much as some would think. Like, Bandana Dee and Meta Knight both have a ton of merit, both would play completely different from each other, and Kirby is a large series where devoting resources to four characters isn't really overdoing anything in the roster size we're likely to get. Maybe adding Bandana Dee has to come at the cost of somebody those resources could go to instead, but there's literally zero reason for that somebody to be Meta Knight even though he's a Kirby character, too.
