As for Zelda newcomers, I'm not banking on it much. Our only other possible ones were two semi-clones in Toon Zelda and Toon Sheik(and no, it didn't mean Tetra in the first place. It would've said that or something heavily alluding to it. This isn't a Roy case where it used FireEmblem because Sakurai wasn't sure on who. This is quite a bit later with scrapped characters. The only questionable entries are Pra_Mai at best, and that's still likely to be Plusle & Minun, despite the odd naming schemes).
Though at least now it's much easier to make Toon Sheik, but other than having a combo of them being transformation characters, there's no real reason for it. It would've been difficult to make either way(Toon Sheik needs a new model, and Tetra cannot be a clone type anyway). Besides that, Toon Link only was easy because he used assets from Young Link as well. Without Young Link, he might've not even made it in. We might've just gotten Ganondorf at best(who may have still been some kind of clone too). To clarify a bit, if we didn't get Young Link, it'd be due to not getting any clones in Melee. So no Ganondorf either.
But yeah, there's been zero hints of any other ones even considered. Instead of new characters, they updated two of the playable ones to resemble different versions(BOTW Link, TP Link, ALTTP/ALBW Zelda, TP Zelda). Ganondorf doesn't count in the same way, since it's not a different person. Nor does Toon Link, since he's a completely different design from Young Link and only counts as a semi-clone of him at best. And as noted, we were going to get a semi-clone of Zelda and Sheik otherwise. Not exactly promising. I honestly would expect another Ganon or Dorf at this point, or even Toon Zelda(or Tetra, or Toon Zelda/Toon Sheik if they find it easier to work with). There's a lot of cool characters, but they're reduced to cameos at best. Hell, even the most notable Ganon, from ALTTP(and games using the artstyle) has yet to get a reference. Which says even more of how little Characters are on the table.
Ultimately, Stages, Spirits, and Items are probably all that Zelda will get from now on. If we're lucky, another Triforce Trio variant. And I say this as someone who wants Tingle and Oracles Impa too. They're awesome choices(also, ALTTP Ganon).