I actually thought they always were? Like, Magneto was Jewish but his kids were raised Romani because of the mom's side? Um, of course, they also were no longer his kids anymore last I recall, so who knows?
And I can't say I'm in love with the notion of Gal Gadot as Cleopatra necessarily, but I think it could be done in a way as to not be just completely offensive. You basically can't just have all the Egyptians be white ... you know, the movie could take the opportunity to suggest Egypt was not just all once race or ethnicity, even then. Which would definitely be dismissed as PC or whatever by some, but honestly I feel like it's your safest bet, if you're going to go there at all.