I'd say Kamala's different enough from Danvers that she basically counts as her own character (as opposed to Miles, who's essentially "here's another Peter Parker" in virtually every respect).  The way I see it, if a character can stand on their own feet without having to mooch off of another character's star-power (and let's be real, Carol wasn't an A-lister until they gave her the Captain prefix [s][and even then her books aren't exactly flying off the shelves][/s]), they're permissible.