It wouldnt surprise me if the next Black Panther film was about a pro-democracy/ anti-monarchy rebellion in the streets of Wakanda and how our "hero" has to suppress it violently or accommodate it.
I think that would be the storyline if Killmonger had won at the end, but that doesn't make much sense with T'Challa since all the tribes [sans Jabari] + the Doras were on his side from jump [everyone wanted him to be King]... and by the end of the movie all tribes [including the Jabari] were united on his side and represented his council, with the exception of maybe the Border tribe (i have to go back and look).
Basically everything was back in harmony in-house, and actually improved upon with M'Baku. I think the biggest thing in the sequel would be less democracy talk and more the protectionism some Wakanda's may feel about sharing certain resources or letting in refugees.
But I don't think they'll retread the whole 'ruling wakanda' thing again, since that was pretty well covered in the first film.