The next six challengers headed to Super Smash Bros. Ultimate may be all that's coming.
According to translations (via PushDustin and Ryokutya2089) of Smash Bros. game director Masahiro Sakurai's latest Weekly Famitsu column, neither he nor Nintendo currently plan to make any more fighters for the game beyond the second Fighters Pass. That will bring the total number of playable characters in the game up to 88. Just to put things in perspective for a moment, that's enough to do 11 huge, chaotic 8-player battles back to back without repeating any characters. Or to allow for 7,656 unique 1v1 matchups, not counting mirror matches.
Keep in mind that Sakurai saying 'there are no plans for more DLC fighters' is not the same as him saying they will definitely not make any more. Sakurai also added that he and Nintendo are not planning any more entries in the Super Smash Bros. series right now. However, Sakurai has been talking about each Smash Bros. game being his last since at least the days of Brawl, so you shouldn't necessarily put too much stock in that either.
The final selection of characters for Fighters Pass Vol. 2 has already been made, Sakurai restated, and he also pointed out that Nintendo made the selections, not him. So don't get mad at him if it's full of new Pokemon and anime swordsmen.
The final character of the first Fighters Pass, Byleth from Fire Emblem: Three Houses, was added to the game in January. We don't know when the first character from the next one will arrive (or if it will actually be Crash Bandicoot). Nintendo has confirmed that the final portion of the second Fighters Pass will be released by December 2021 at the latest.
