Let them all go with one proviso. When it all goes wrong they can't come back.
If its one big league with no promotion or relegation they will soon get bored. They are all used to winning and being top of the table. But someone is going to become the perennial mid table fodder. Someone is going to be bottom and lose every week. Their fragile egos won't like that they will want to return to a league where they win most of the time. Thats when you tell them "Nope, sorry, you've made your bed now lie in it"
Meanwhile everyone else enjoys a much more competitive league which isn't dominated by the same few clubs.
Bring it on
Problem is none of that will happen because money is king. As long as the billions are rolling in no one in authority gives a rats ass.
Football is gone, never to return