I’ve always advocated having one MLS team to serve basically as the US men’s national team. The best players, unless they play in Europe would basically play on this team and they would be coached by the USMNT coaches and implement their style of play.
That’s a great idea. Or as a related approach, they could mandate that 60% of the players come from the top two MSL teams, and the other 40% can be the best who are playing abroad.
But that's not good for the league - you've got to split up the top players or you wind up with one team with all of the talent,and no real competition to play against.