Alright so since I gave my more objective assessment before I'll be more subjective now.
Lucario kinda feels like dead weight right now, if I'm gonna be as blunt as possible. The discussion around him is never about how fresh and unique and fun he is, what he's actually providing to the game, it's mostly about how obligatory he is. I mostly get that for series that are less fruitful as it stands - like alright, Isabelle is technically not reinventing the wheel but you kinda gotta have her here, Animal Crossing doesn't have a lot to begin with - but Pokemon has like 10 characters in Smash and so many of them are bold, colorful, exciting additions that bring something extremely dynamic and cool to the table. And then you have Lucario, who apparently needs to be here and feels like a relic.
I want Lucario here if they can refresh him in a way that feels meaningful. He has loads of potential that could make him very fun and flashy. What I don't want is Lucario's awkward current moveset to come back just because it has to, when Pokemon has since delivered on much more intuitive and creative characters who are technically lower down the food chain but are offering so much more to this game dynamically. Ask the average player if they want Lucario or Incineroar back, based on who they enjoy playing more, and I'm confident that the majority vote will not be Lucario.
I agree that Lucario's moveset is pretty whatever. And I would love for Lucario to get a bit of a rework. The rage mechanic basically took his hook. And, I'm not saying he replaced Mewtwo, and I'm not saying they play they same, but thematically they have some similarities, as well as a few very surface similarities in a couple moves, so in Brawl, when Mewtwo wasn't there, it did help Lucario stand out more.
Having said that, I don't think those problems will affect his priority much. I think being Lucario (and to a lesser but still present extent, seniority) will keep him from being in proximity of the chopping block, unless we lose... really significant chunks of the roster.
As for your point in asking who people enjoy playing more between Incineroar and Lucario, I agree. But I wouldn't be surprised if, in spite of that, when asked who people (the general audience, not people as diehard as us or competitive players) would rather retain, Lucario wins. Because for people who really care about and use Incineroar, that's one thing, but I think familiarity and general popularity is a powerful thing, more so than being more fun to play.
This is contrasted with characters I consider major additions who may have flawed designs, but are massively popular. This isn't me saying that Ganondorf, Sonic, Little Mac ought to be cut. Because despite everything, a LOT of people actually like playing these characters, and honestly I think they are filling more distinct valuable archetypes despite it all. Lucario, and another character I want to touch on, are characters who are massively important on paper but I think struggle to find a meaningful roster niche.
I actually think they might take this opportunity to give Ganondorf a proper full rework, since TotK Ganondorf is a thing and as popular as he is. My fear, however, is they do this instead of giving Zelda an actual newcomer, but... I guess something is better than the usual nothing.
Sonic and Little Mac sadly I don't see getting too many changes (maybe Little Mac is tweaked just to be slightly more viable), but what I can see is getting a Sonic clone who alters the moveset to some extent, so there's just... a bit of a rework... even if Sonic doesn't get it. Probably Shadow if the moveset doesn't change that much, but if they're willing to make bigger changes more akin to a semi-clone, possibly Tails or Knuckles.
The other character is Bowser Jr. Bowser Jr is everywhere, I cannot stress this enough - one of the biggest Nintendo characters to debut in the 2000s, and he is in pretty much every Mario game nowadays. He is far more frequently prominent within the Mario brand compared to Rosalina, another secondary pick for the series in Smash. Mario, like Pokemon, has a huge crop of characters likely to be scaled down. Both of these characters are somewhat unpopular to play in Smash, but between the two I think its obvious that Rosalina provides the more distinct gameplay hook through her puppet oriented gameplay. Bowser Jr feels more derivative and maybe not all there. And people seem willing to address this, Rosalina is often prioritized over him in heavier cut scenarios largely for this reason. Meanwhile Bowser Jr is, inarguably, one of the modern series mascots present across the span of games, multimedia projects such as the amusement park and so forth. If we were to apply the same toward Lucario, and cut him in favor of keeping Incineroar or Jigglypuff, what makes that especially egregious in contrast?
But still I think many people believe both Rosalina and Bowser Jr still have a place in Smash moving forward, and I have the same sentiment toward Lucario. I think as long as we have at least 7 or so Pokemon he'll probably be a part of it. Again, I'm open to them doing something new with Lucario, and I'll gladly welcome him back if that happens, but I have my doubts about it depending on how much roster space is provided. And if he comes back largely unaltered then... I don't know, he'll be one of the least popular characters again. Just my two cents.
Yeah, I actually think we're much likelier to lose Bowser Jr than Lucario. Rosalina too, tbh. Obv I think PP and Doc are likeliest to be cut, but then I think it might be Jr. It could be Daisy, but I think she'll stick around. Not due to being a clone (though that helps), but due to her increasing prevalence in the series.
Meanwhile, despite his uniqueness, Jr seems to be lower priority in the Mario series, and I do think them getting more than two cuts is entirely plausible. I'll be real, I can even see both him and Rosalina being cut. To qualify that, I think losing one is likelier than both, but I don't think either is safe.
With Pokemon, I just think Lucario has a much better buffer, where Incineroar, Pichu, and probably Squirtle, Ivysaur, maybe Jigglypuff, and potentially even Greninja would be before him.
