Age of Calamity: Lana & Cia?

Right now there is no real reason to believe that any of the 29 playable characters from Hyrule Warriors will return in Hyrule Warriors: Age of Calamity. Of course we don't know for sure, because we've only seen very little of the game so far, but it does seem like the focus sits entirely on Breath of the Wild, where characters like Link, Zelda and Impa are getting new designs and movesets based on the latest and most successful episode of the Zelda franchise.

This would be quite unusual for a Warriors title, however, where Koei Tecmo likes to bring most of the previous cast back with every new iteration. Having many playable characters is kind of part of the deal. On the other hand, putting characters like Toon Link, Marin or Midna into Age of Calamity might feel very out of place... Hyrule Warriors became a mashup of all sorts of art-styles, where 30 years of Zelda history were coming together in one big all-stars title. And we already have all of this on the Nintendo Switch with the Definitive Edition of the game, so Koei Tecmo could focus solely on Breath of the Wild with this new Warriors game to create a more cohesive and serious experience.

But if characters from the first game swere to return somehow, it would make sense to re-design them in the art-style of Breath of the Wild to make them blend in better. The biggest candidates for this are arguably these two ladies:

Lana and Cia, the two observers of time, keepers of the balance of the Triforce. It makes sense that they still would exist during the era of Age of Calamity or at least have somehow access to it with their magic. And they both could get full re-designs based on Breath of the Wild with new movesets and everything. Their magic always felt quite "technological", like for example the Summoning Gates, where this could blend in quite well with the whole Sheikah technology theme.

I would not expect them to appear as part of the main story, though they could possibly be used to create alternate realities, where the Champions didn't fall or where characters from 100 years are summoned by them and so on. They could act as the catalyst for the big, new Adventure Mode.

This could also create a bridge to a possible "Hyrule Warriors 2" in the future, on Nintendo's next console, where everything of Hyrule Warriors and Hyrule Warriors: Age of Calamity would be coming together...