LOL
I don't want it to happen but a Euro League would be a success TV wise. And, sadly, it is bound to happen one day. People have been talking about it for well over a decade now.
It won't work for the reasons I listed, and because the clubs involved will sabotage it themselves. American style closed leagues work because the teams are a collective. There's a salary cap, entry draft, TV revenue sharing, etc - all designed to create parody. You think Real Madrid and Juventus are going to agree to that? It will only be a few short years until the bottom clubs of this new league (which Arsenal will be if still run by Kroenke) will be begging to rejoin their domestic leagues. The super league may do well with newer fans in international (Asian) markets, but the long term fans of teams who are use to regularly finishing in high places will not enjoy becoming bottom dwellers of this new league. Not to mention the loss of local rivalries. I think a lot of the disinterest you see in college sports today stems from conference realignment, and it is hard to think of any big brand that has benefitted from destroying old rivalries. Tradition matters with something as tribal as community based sports.
Man U, Liverpool, etc. will also be forfeiting the English marketplace the moment they leave. If the clubs goal to is to become a global all-star team, then okay, but I expect those clubs to lose a lot of interest, fans, and money back home. Also with UEFA being frozen out you could see individual FA's giving these clubs the boot as well. Which means that SuperLeague players may not be allowed to play in UEFA competitions, for club or country. Naturally FIFA would welcome them to the World Cup, but the Euros will suffer tremendously.
Now this is assuming that the other 15 (apparently only 5 of the Sky6 are invited) PL step up and boot them from the competition. Which would make sense since the leaving clubs would not give precedence to the domestic league since there is no incentive to finish higher up the domestic table. These break away clubs would also want the fixtures scheduled around them, especially if the new SuperLeague tries to take over weekends.
You could also see certain domestic leagues refusing to sell players to the super league teams, which would starve the new league of young talent for the first couple of years. And as I pointed out earlier, the inability to loan out backlogged young talent would severely hurt the pocket books of these "super teams" as well. I get that its a short term cash grab, and it appeals to brands with no competitive ambition, but in the long term this league will severely hurt European football. The game will have to shrink dramatically, and interest in Europe will dwindle. Hundreds of millions of fans will no longer have any interest in the European pyramid.
That all being said if I was MLS I would be licking my lips around now. The closed SuperLeague will kill off all the other teams (which is its goal BTW, to end competition) and MLS could set itself up to be the one rival to this new league.