I have mixed feelings on the Chun-Li/Tales leak.
On the one hand, both characters make a lot of sense. Chun-Li is the first lady of fighting games and one of gaming's biggest female stars after Peach, so she has that same star power Sephiroth did in being gaming's most iconic baddie that's not part of Mario's rogue gallery. Likewise, Tales is the next biggest RPG not in Smash yet and both Lloyd and Yuri could bring a fun and unique moveset.
On the other hand, I think we're biting a little too hard on what's essentially a greentext leak. Both Erdrick and Steve were already heavily discussed in Smash Ultimate's early DLC period because Vergeben had given his blessing to some kind of Dragon Quest and Minecraft content, so going "Oh yeah, those two were planned for the base game but fizzled because lawyers gonna lawyer" and being right wasn't a big jump. Similarly, I believe that post came after the Seven Squares leak, meaning that the post's author could have looked into the line-up and thought the Luminary and Sephiroth were the most practicable options and would make Square the happiest. There's also the issue of Min Min's kicks feeling like a deliberate attempt to make her more like Chun-Li, which raises the question of why this would be done if we're getting the real Chun-Li in the near future.
I also think it's worth noting that, even if Chun-Li and Tales were cut from the base game and Cut Content theory is true, that doesn't necessarily mean for a fact that those two are next. We already know that Alucard, Decidueye, and Rex were all considered for the base game and there are probably dozens more that we don't know about. For example, it's kinda taken for granted that the Chorus Kids were, if nothing else, heavily considered for Smash for Wii U and 3DS, as the community deduced this from the Gematsu leak's otherwise strong record and the fact that Rhythm Heaven is lumped with the series that have fighters in Smash for 3DS' code. Characters can come very close to making it into the game with Sakurai ever publicly acknowledging their existence. There's also the fact that Fighter's Pack 11 could very well be another promotional pick for a 2021 release, so that further reduces the possibility of both Chun-Li and Tales coming down the pipeline.
I don't know, I could definitely see it happening, but I think people are latching on to this way too quickly.