As long as we're talking about fantasies, I'd rather we keep the whole country but split off the big cities into their own walled off protected zones or districts.

• The special districts are operated by their parent state, which may decide who may enter and leave the district.

• Federal regulation determines the borders of the districts based on a population density calculation.

• They are treated like DC as far as getting no representation. They do not count towards their state's electoral college votes. Maybe each one gets one vote and one representative, but no senators. (they all vote Dem already so that won't change anything)

• Every year we will hold an exciting nation-wide combat tournament with two players from each district participating, to remind the districts why they exist and what that they lost.