Given the choice of watching weekly football against the top teams of Europe or the lower reaches of the Prem, I think some form of European league is inevitable. However, the politics of who will run it, whether it should be performance based or subject to political/geographical selection, and how to allow promotion and relegation within these constraints, it will take a long time to resolve - Brexit has probably delayed it by some years. So maybe not in my lifetime, but eventually....
And as African, Asian and North American teams develop, it could itself become a feeder for a genuine World Series league.