Peter Lawwell is on the European Club Association board, as such you'd expect he has some insights into what is planned regarding European competition, so Celtic pulling out of this is probably quite telling.
There were talks at quite an advanced stage between the Belgians and Dutch to create a unified 'super-league' with clubs from both nations competing. I suspect Covid has interfered with its plans but it was being reported that UEFA were open to it. The Dutch and Belgians are neighbours so the extra travel isn't a big issue, 60% of Belgium speak Dutch and they use the same currency so commercially, culturally and logistically it makes sense. For me it makes sense for the Danes, Swedes and Norwegians to get together for similar reasons. But we're being shoe-horned in as no one else wants us. If the the direction of travel in UEFA is amalgamating domestic leagues then clearly a 'British Isles' league is the obvious one for us to join, but I can only see that happening if the big 6 or so English sides leave and join some NFL style closed league with selected German, Italian and Spanish clubs. We might then be attractive to sponsors and broadcasters playing in a league with sides like Aston Villa, Wolves, Leicester and West Ham.
UEFA and the big club sides are involved in an on-going power struggle. UEFA want to keep smaller football associations, like Scotland, onside as smaller FAs help keep the big ones in line on important votes. Even the biggest clubs are very nervous of unilaterally leaving UEFA and going it alone, so it's likely to come down to how much UEFA are willing to give up and what compromises the bigger clubs are willing to accept.
It's important, I think, that three of the big 6 English sides, and a number of Italian sides have American ownership or substantial influence now. I suspect they'll be pushing very hard for a closed league structure with guaranteed clubs and no relegation, as works in American professional sport. I also fear it's a matter of when, not if, this happens. I can't see any scenario where we're part of that.