This might be too close to ascended cats, but I think Seraph cats could be interesting! Instead of having big wings, they'd have wings for ears that cover their eyes (or not, if that's too hard to make look good) and little wings near their paws! Maybe some tail feathers too? Either replacing the tail or added onto the tail.
And as for something a bit less imaginative, I'd love to see the Karpati mutation added! It could be a variation of white, since Colorpoint is like that here, and this seems to be temperature based just like Colorpoint is.
Here's some rough visuals of the basic ideas! I tried to match the visual style of the markings for Karpati, but I struggled making the feathers for the Seraph Cat owo"
Also loving the bug cat ideas I've seen scattered here, they look so fun!