Mario + Rabbids Kingdom Battle - Here's rayman!

They did redesign and bring him back for Rayman Mini just last year, so they do still remember he exists.

Actually, now that I looked at it more, it may be a corrupted Rosalina, or maybe Rosalina under some kind of curse (hence "Cursa").
The feminine hands, the galaxy under the dress, the broken star pendent (plus the motivation being related to the lumas), the hidden face, Rabbid Rosalina is here but not Rosalina herself, etc. It would be like how the Megabug corrupted Bowser, so it would match with the past villain as well, with Rosalina eventually being uncorrupted and becoming playable to defeat the curse itself in the end.
Plus, having to fight what is essentially the ruler of the universe would be a good series escalation and could result in some cool imagery and fights, similar to how Shadow Peach did from Paper Mario.