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.)
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.