I don't think it would collapse. But it would definitely play second fiddle to this new league, at least in terms of tv revenue and sponsorship.There would be a hit to revenues. The PL would have to think "creatively". However the PL is a strong product so there is no reason why it would collapse.
The way these people operate, they would set up the league and pull up the ladder behind them.
Global exposure to the premier league would be limited.
If it happens and coincides with Everton moving in to a new 50k stadium, there could be real cause for concern.
At the moment Everton are a well established part of the most popular football league in the world. The club has a good foundation and can use that to move stadium/attract investors/sponsors/grow it's global reach. All that changes if the PL plays second fiddle to a European super league.
Theres a romantic notion that we can all go back to paying a tenner in to watch games like pre Premier league and we don't need all the tv and fanfare stuff that comes with the premier league. but there's no going back to your grandads generation.
This would be signing up for a glorified Championship that won't pay the bills for our new stadium.
Not for me.