I agree that new rare hatch colors would be cool! I like the striped idea. I’m not sure I quite agree with the vitiligo suggestion, though, because that’s a real medical condition that can cause serious distress for some patients. I worry that making it into a hatch color could be considered offensive to some. (Also, as a side note, vitiligo is the absence of pigment, not the presence of white pigment.)
Vitiligo is a medical condition, but pinto or piebald is an actual coloration in animals that splashes white patches over the normal coloration. it would be super cool effect to apply over creatu!!
I'm worried that calico is too similar in concept to these -- even if they're not all applicable to each Calico, Calico has portions of each in certain creatu, i.e. piebaldism in Valabex and Gondra, and stripes and brindling in Drindian.