The constitution is 250 years old, and while it was one of the greatest documents in history when it was written, it's aging. It was written in a time where the goal was conquering America. The right to conquer was implied. Until that's changed, neither will America.
It's much more structural feudalism and the New Feudal Lords of America were all white. They sometimes allow minorities marrying into the family, but if they don't toe the line and kiss the ring - they're gone. Look at Harry and Meghan. The Windsors need fresh blood but they refused to kiss ass.
But if they needed Harry so bad, they wouldn't have let him go in the first place. William and his kids were always going to be the ones to succeed the throne and seem to be all the Windsors care about.