Let me preface this with the confession that I was the one person who supported the Super League.
But hot take and this in not a likely prediction or anything, but very much a hot take.
If a major change in the football landscape is incoming it's the fifa club world cup gaining relevance. I say this bc if Saudi Arabia can have 6 teams stacked with top players and a decent league around that you have another massive league, meanwhile Qatar and the MLS are attracting top players too.
If there can be 5 Non European leagues which have 2 teams that are UCL level an expansion would make sense.
But if that happens, quality players will be spread across even more leagues and the bottom half teams across the European clubs will get worse and worse, clubs like Werder Bremen, Rayo Vallecano, Empoli cannot compete at a decent level in such a world.
Best case scenario, the domestic season becomes an 18 game season with 10 teams in the top division with the fifa club world cup in whatever way its formatted being the primary revenue generator for top clubs.
This could make the UCL either another competition or it could make it the lower tier competition. Perhaps smth like the Euros even.
MLS will never be relevant globally. It's a retirement home for players well past their prime, or those who are ready to jump to a lower-tier European league.
And as far as the Saudi Clubs go: pretty much the same. They have no long standing history or big enough fanbases. As soon as all the football mercanaries that go there now either return or retire it'll be dead in the water. So technically they'd have to keep buying players but their league won't be relevant just because they have.few big names.