I honestly wouldn't mind if this Smash is ported ad infinitum and they just add new characters to this. This game has so much content it's insane.

We keep talking about reducing the cast and you keep suggesting to expand it. How about just getting rid of Dark Samus? Do really need it? Lets pretend that the next smash bros was going to be reboot with a cast of 30 playable characters. Lets pretend only 10 of those characters will be returning characters. Why should Dark Samus Return? Between Ridley and Dark Samus, Ridley all the way. Why have Dark Samus take up a slot?

I think it's safe to say that we won't see a Smash game again with "Everyone Is Here!" Including Echo Fighters, we're over 80 fighters once the Fighter Pass is done. And then there will be more fighters still.
I think it's feasible that the next Smash could have almost the same amount of fighters or slightly more, but a lot will be cut (massive cuts I'm thinking to third-party characters) to make way for some new characters. A Smash roster at 100 or more fighters (even with about a dozen echoes) isn't a good idea.

That would have just taken more time in development and we wouldn’t have had the December release. You would still need to balance the attacks for both 1-on-1 and free-for-alls and make sure there’s no bugs/glitches that could hinder the gameplay experience. That still takes man hours. 

While i I understand some people’s issue with the large roster, Ultimate is something not to be taken for granted. It’s an incredible feat to have a crossover of this magnitude. Plus, the roster is remarkably balanced. Tournaments have shown that there is room for a variety of characters to be great. I think Sakurai is right that something like this may never happen again. And I think that’s fine. But that should not take away the fact that Ultimate is something incredible. It ranks up there with Avengers Infinity War/Endgame, JLU, the Silent Era/Early Audio Era Monsters, Marvel vs. Capcom, etc.

Idk if it’s being driven into a corner, I think it’s more that Sakurai just continues to push for bigger and better with each installment he’s involved in. As he stated for a long time, he treats each developed game since 64 as his last. So he will put his best foot forward every step of the way until the game is completed. That’s how he is.

People mix his words as if he wants to make Melee or Brawl his last game.

In fact, it’s been an issue that people seem to have twisted his words in the past.

here are some examples in this article by Source Gaming:

https://www.sourcegaming.info/2015/07/10/sakurai-didnt-say-that/

All characters in Smash are highly requested..... Ok fine, maybe not Terry Bogard. What makes her Special? If Dark Samus added to next roster, its taking up a slot.  I gave you conditions and you completely ignored them like I knew you would.

Dark Samus doesn’t necessarily take up a spot in Ultimate and it wouldn’t in the hypothetical next game. Sakurai even said clones (later known as echoes) were like extras or “free dessert.” DS is a character that the dev had some time adding into the roster without spending too much resources and time. Sakurai already makes the finalized development plan for his games, thus, the roster would be set before the actual development starts. Things can somewhat change and echoes can be added during development.

I think less may be more in this case. I mean fans are really scraping the bottom of the barrel with their most wanted characters at this point. Bandana Dee, Waluigi and Geno to name a few. Not only characters with no personality, but they barely have any characteristics.

I can see the next few titles losing and gaining characters, not unlike Brawl and Wii/3DS (fucking hate the name for Smash 4). Then, when everyone is itching for it... Smash 9 will be Super Smash Brothers Penultimate.

Odd thing to say. I would like to see a spin off in Smash Brothers. Maybe a Power Stone style Smash game as there next title.
Honestly Ulimate is enough, there really isnt any reason to make another with a smaller roster. Unless they can leap and bounds improve the visuals.