Additional note regarding the Desert teaser: Ursula does check out thanks to Eirika (although few expected another alt of her in the near future), same for Merric. And the next RB rotation leans toward an Archanea Harmonic lead, while the teaser hints at Khadein, desert and magic.

Personally having noticeable signals on Phina (ideally as a F2P dancer, could ferry Navarre who checks out VA-wise), Tethys (VA check, fitting if the Harmonic is a dancer), Linde (thematic fit), but also two of Claude/Bernadetta/Petra along with the presumed MByleth.