A few thoughts assuming that the Super League moves forward:
1. The Super League doesn't strike me as much different than the expanded Champions League beyond the permanent member structure. If the expanded Champions League can fit within the schedule, so can the Super League. The closer the CL gets to a Super League, the more likely a Super League becomes.
2. Bayern and Leipzig will join if the original 12 members can survive the initial legal challenges. Don't care what they say now. Elite teams that don't join will fade into irrelevance and place themselves at a massive economic disadvantage. What is PSG's value if they only play in Ligue 1 and the watered down CL? Hundreds of millions less. It makes sense for them to oppose the Super League now because of German and French football politics, but if the Super League becomes inevitable they will use the foregoing arguments to jump ship. "We didn't have a choice."
3. The EPL really isn't in a position to kick out the 5 clubs that matter in England and Tottenham. Same with Serie A and La Liga. Those threats strike me as complete bluffs. The EPL without the Big 6 is basically the Championship. La Liga is Barca/Madrid.
4. Similarly, the World Cup and the Euros can't disqualify the best players in the world from their international competitions. They would immediately be rendered meaningless. As others have analogized, the new competitions would be akin to the men's Olympic soccer which no one watches or cares about.
5. I would be surprised if the Super League ultimately includes any non-permanent members. You are either a part of the closed system or you are out of it.
6. The leading global football organizations all sold their souls to monied interests a long time ago. It is difficult to conceive of a more corrupt organization than FIFA, a more elitist one than UEFA or a greedier one than the EPL. They allowed the leading teams to be acquired by their peers in greed and corruption and are now SHOCKED that the club owners want to keep all of the pie. What did they expect when they allowed Man United to be acquired through an LBO or Chelsea to be acquired by a Russian mafioso or Liverpool to be acquired by private equity vultures or City to be acquired by a petrostate?
7. The last true outsiders to make the CL final were Porto and Monaco in 2003-2004. All finalists since then come from the 12 other than Bayern, PSG and Dortmund. We are a long, long way from Nottingham Forest beating Malmo in the final of the old European Cup. The irony of the proposal is that small teams may actually be able to win the watered down CL.