Honestly, with a 70+ character roster, I don't know what more do people want. The roster is already absolutely huge as is and if the currently known roster was the final, it would already be an insane roster. But we're getting more and potentially even more through DLC and other updates. I don't think anyone here is appreciating the magnitude of that.
After Smash 4's release, there were only three things people were upset about:
1. No Ridley
2. No K. Rool
3. The cuts (and lack of returnees)
If this is indeed the final base roster, we got every veteran ever to come back, as well as both Ridley and K. Rool. After Smash 4, I was very pessimistic on Ridley ever making it in. We got the two most highly requested newcomers during much of pre-Smash 4, Castlevania joining the fray (with a lot of content to boot), and not a single veteran being cut (with even the likes of Pichu and Young Link returning).
I bet if you went back in time four years ago, (when Smash 4 was first released) and told your past self that this would be the base roster for the next game and that it was causing outrage because "it was not enough", I bet most of your past selves would view the Smash Bros. fanbase of 2018 as being filled with the most petulant and spoiled babies of all gaming fandom.
Every veteran ever. Ridley. K. Rool. Castlevania. New icons like Inkling and Isabelle. And bones thrown to fanbases that did not lead the back (but were certainly there), Daisy, Chrom, and Dark Samus. Even Ken (assuming he is in) himself is an all-star especially for a franchise with as much clone characters as the Smash Bros. series. Sakurai did the best he could with only an allotment of 11 newcomers and only five truly unique newcomer slots, and yet created something very satisfactory.
There are no potential newcomers that had the level of support that K. Rool and Ridley did back during Smash 4 that did not end up making it in. The closest is maaaaaaybe Bandanna Dee and that is only on the Japanese side of things. Isaac is the closest one on the Western side, and even then he falls short of what Ridley, K. Rool, and Mewtwo were during pre-Smash 4 (both Ridley and K. Rool had support topic views into the MILLIONS).
Inkling and Isabelle covered things from the casual perspective (though Inkling certainly did have a ton of requests from core Smash Bros. fans), while Ridley and K. Rool were obviously the biggest (pun intended) guys left after Smash 4. Castlevania is the one third-party franchise that is as connected to the Nintendo brand of consoles as Mega Man is. Daisy, Chrom, Dark Samus, and Ken (assuming he is in) are delicious free desserts for many.
Even if there are only two more fighters, this is a fantastic base roster.