The problem with this is that going off of what Sakurai has said and implied, there is nothing that shows such negotiations happened. For instance, Sakurai was still pretty bullish on saying that 'Everyone is Here' is probably not happening again
even recently, so if such negotiations happened you'd think he'd be more positive on the chance of it happening again, not less. We also can't forget he's also semi-retired which also doesn't really mesh with the possibility.
As of now there's nothing suggesting they did negotiations for a future game before closing and instead more evidence to the contrary. If Everyone is Here happens again they'd likely have to renegotiate, we can't assume otherwise.
I have always said the full quote you are using is a lot less of a decisive "we can never do EiH again" than people like to say.
Here is the full quote.
"I think we’ve reached the limit, at least in terms of volume of content and fighters. Basically, if I were to have the opportunity to work on another Super Smash Bros. game, that means we would have to shrink the roster, but we need to think about whether fans would be pleased about that.
Also, I’ve been doing too much of the work myself, so I’d need to resolve that, too. The current Super Smash Bros. has too much of my personality poured into it. In order for a long-time series to continue thriving today, we need to think about eliminating the series’ dependence on just one person’s vision.
Of course, this is the way it is now because we weren’t successful in splitting the vision between multiple people before. This would be a challenge for the future and something that needs to be discussed with Nintendo, if there were to be a next installment in the Super Smash Bros. series."
Even in the first two lines, Sakurai is ambivalent rather than bullish about cuts. He says it could very will be the case that cuts happen, but they would have to ask whether that would be what fans want. Everyone is Here happened because Sakurai saw that was what fans wanted. This is far from the silver bullet that kills EiH that some people like to pretend it is. This statement, given the context behind EiH, is at least somewhat at odds with itself. For a completely new game, EiH will probably not be feasible. But of all people, Sakurai knows that the Smash fanbase wants its returning veterans back. The rest of the quote also focuses on Sakurai's involvment in Smash, and how he can't carry the series on his back forever.
The most damning thing no one likes to talk about is how Sakurai keeps discussing the next Smash with the word if, rather than when. I know for us, it is easy to just assume that Smash is going to keep on pumping out a new game every single console. But Nintendo has shown that they are not exactly unwilling to do a port to Sakurai in the past. If Sakurai did not want to do Brawl, Iwata noted they would look at porting Melee but with Online gameplay for the wii. Now, Nintendo in 2023 and 2005 are very different beasts. But it is not like they have been adverse to ports in the past. Think of how much of the Wii U's library has been ported off of the Wii U. Plenty of games either got ported or used their Wii U release as abase to work from, Smash included. I think this is where the crux of an Ultimate Deluxe comes from, in the same vein of Mario Kart 8. Maybe Nintendo will choose to take the path of least resistance, like they shown in the past.
An Ultimate Deluxe is also a good solution to the major issues Sakurai highlighted as well on the human side. Sakurai is not getting any younger and it was a challenge in the past finding anyone to share that vision of Smash with. An Ultimate deluxe is a low risk testing grounds for a future Smash producer taking the reigns from Sakurai. It still has a lot of work that needs to be done, but far less than reinventing the wheel. Its not that crazy to see them taking this route when Sakurai spends even more time discussing his concerns on the human side of things than cuts. It is easy to just harp on those first two sentences and say that EiH is dead on arrival for the future, but the context is very different. I read this quote as a man proud of his accomplishments but is worried about the future of the series. He knows that EiH is going to be difficult to maintain, but he knows a large part of the fanbase does want to avoid cuts. He knows that a Smash series completely resting on his vision is impossible, but it will be hard to move past it.
It is a lot more complicated than just saying his ambivalence on Everyone is Here means no negotiations for the future could have taken place. We obviously can't say for certain, but the precedent of Smash 4 into Ultimate does give us some idea that it is not off the table. Ryu, Cloud, and Bayo are the obvious examples, but we have evidence it goes deeper than that. Steve supposedly was in talks since ~2015. Sephiroth was in talks well before anything from FFVII ReMake would be feasible to use. If they were negotiating things over five years in advance when it comes to Ultimate DLC, having some form of negotiations in play for a hypothetical new game is not that out of the question. It doesn't even mean that every third party is set in stone to come back. Maybe at least one of the contracts did not have that potential future installment in mind and would have to be renegotiated. Or maybe Sakurai is not even talking on the third party side of things and thinks some first parties would have to inevitably get the axe due to being lower priority newcomers. It is nowhere close to a bullish condemnation of EiH, let alone contracts potentially allowing any third party a future appearance being completely off the table.
Ultimate but replace the Story with the most polished refined new and improved take on Melee’s adventure mode that I dream of every night when I close my eyes and you got a deal.
No takebacks.
You get your Melee style adventure mode alongside WoL. Bosses from WoL (or if it gets extended) get reused for this as well. Plenty of the stages will still be similar to the melee one and not a full on level traversal.
My biggest fear is if we get a reboot with a hugely scaled back roster, that basically eliminates the possibility of ever seeing B or C tier third party guests and the few we still get will only be from AAA hits. A lot of my favorite characters are below that AAA tier so it would kill a lot of the excitement in future Smash speculation for me. The only solution I see to that other than building on Ultimate is a rotating “Nintendo vs” model that gives us a fresh set of third party newcomers in each game based on that particular theme.
Even if EiH is not coming back, a hard reboot is almost certainly not happening. Nintendo is not going to reinvent the wheel when Smash Ultimate is the best selling fighting game of all time.