Ok, let's just say this European League was formed & the sky 4 go in it. While different teams would be competing for the title of national champions, what's to say that after a few years a bunch of the teams remaining wouldn't build up a similar standing at the top to what the sky 4 have now? There's every chance that would happen & then the league would be back to the way it is now only without it's strongest teams & everything that comes with them.
All of the best players in the world would demand to play in the European League & the vast majority of commerical money would be pumped into it & so the teams that weren't in it would have no chance of ever competing with them. All the other teams would just have to accept that they'll never be able to challenge at the top level, no matter what they do. Even with the sky 4, there's still a chance that others can break into the top 4, consolodate & then build on it. It's a small chance but it's a chance nonetheless & that chance would be completely gone if the above happened.
A European Super League thing would dramatically change football forever & while different teams would compete for the title in some countries, the novelty would soon wear off & I truely believe it'd kill the game we all love for everyone but fans of teams in it