Boseman would be great. I think it's more important to get a great actor who can bring T'Challa to life in a charming compelling way, than just being African for the sake of being African. Besides, I don't think anyone's actually choosing Africans, but British guys with African last names. I don't really see how that's any better for the movie itself.
That said, Chiwetel is still THE choice, because of what he's done, not how recently his lineage was in Africa. If his name was Brian Gallagher, he'd still be THE choice.
Yeah, no one's figured out how to make a likeable isolationist nation. See Atlantis, Themyscira, Attilan, Latveria and while we're at it, Cuba, North Korea, and Iran. You can have an isolationist powerful nation, or a likeable powerful nation, but not both. Something about people who say 'I'm better than you and I don't need anyone' is a turn off, rather than a game changer, for some reason.
I think the focus for a Black Panther movie should be on T'Challa, and that Wakanda should be toned down adapted in many of the same ways that Asgard and Stark Industries were.
But these are things I've said before in
The EVERYTHING Black Panther Thread