I think where the ESL will fail is with the fans and with the of playing similar strong teams over and over again leading to the possibility of boring draws because the strength of the teams equal themselves out.
Firstly with the fans, clubs would be expecting their fans to travel to multiple countries every week. Such a thing is not financially possible for the average fan. This would start critics off by saying that not only would the ESL be a rich team/rich owners game but also a rich fan's game because only the wealthy would be able to afford going abroad each week to an away game.
The next problem would be variety. Two teams of equal strength, canceling each other out which leads to a draw. How long would fan's put up with that? The beauty of the current system is that no one can predict the out come of a game when a top team is playing a lower ranked team in the league. How many times have we seen the top teams from every top league in the UK and EU get beaten by a team that is in the relegation zone. We see it time and time again. Not good for the fans of the top team but great for the fans of the lower team. This unpredictable nature is what makes league football so great. Look at Bayern, winners of the league the past 11 years, has one of the worlds best strikers and yet lose against lower opposition thus affecting them winning the league for the 12th year. In England, both Liverpool and Arsenal on a drive to win the league, losing and drawing against lower opposition teams affecting them from winning the league. This is what fans want isn't it?
Liverpool's dominance of the 70's, people were getting fed up of it, Man United's dominance in the 90's and early 2000's, people were getting fed up of it, now Man City's dominance, people are getting fed up of it. Would such a thing happen in a ESL? Also, what about the fans no longer seeing their team dominate year after year. Would they be happy? Man City, 6 league titles in 7 years, Bayern Munich, 11 league titles in a row, PSG, 10 league titles in 12 years, Real Madrid, 4 league titles and Barcelona 6 league titles in 12 years. In a ESL league, that would all stop, would fans of those clubs be happy with a league where their team is not always winning it like they are now? I do not think so hence why in my opinion fans would quickly get fed up of the ESL want things to return back to how they were.