Just remember that they made a ton of slots as placeholders.
There's no requirement to fill that data. Sakurai's only statement right now is "this is the final DLC for this game". I'd go with that as most likely. Of course, it can change. Echo Pass, a few extras, etc. But I wouldn't count on it either. The Switch's lifespan and Ultimate's are already nearly over, so moving on also makes sense. Also, considering we've taken 1 year to get 3 characters out of 6, and it's not actually because of the pandemic(which didn't help either), it looks more like they plan to fully hit the deadline and end it there. Besides, Sephiroth might be the first character in this pass that didn't require an extra amount of time. He was shown in general much much faster than Steve or Min Min after the two. Who knows how mechanic-heavy the rest could be. Geno I doubt would be much outside of timed hits.
I want to note I don't compare to this to previous DLC situations because it's not the same. There were no passes outside of Smash Ultimate, and that was both less characters, only one with hefty mechanics(Hero), and the pandemic wasn't even a thing yet to deal with. Besides that, Smash Ultimate's various reveals were different from 4's. Overall, I'd say they're a different kettle of fish.