It's hard to predict what would happen. If La Liga expels Barca and Madrid, they have to proceed with the Super League because they could as well cancel their club if they had to play in the last division. The demand for football will remain, the only question is where the attention will be directed. Will people watch the Super League or stay with the league itself?I don't think it's a 'staged' action, I think the clubs involved in the Super League see it as a win/win situation. Either they stay in the CL on their terms, with more money and influence. Or they actually start the Super League they've been planning, and get more money from that. I just get the impression the clubs aren't that advanced yet with setting up this Super League, which would mean they most likely would want to reach a better agreement with UEFA for the CL for the next few years. But there's a possibility this blows up so hard they will have to proceed with their Super League, I just don't think it's very likely at the moment.
I don't think the national associations would call their bluff. Barcelona and Real Madrid bring in like 80% of the multi billion revenua for La Liga, why would the same La Liga punish them so severely? That would be financial suicide. Similar goes for the Premier Leauge and the 6 biggest clubs. It makes no logical sense at all.
So like you say yes, you get the impressions that the clubs involved don't think the associations will be so consequent.
Right now, it's clear which side has the moral high ground and at least for European fans, this will play a huge role. Football support is still heavily dependent on where you grew up. Madrid and Barca draw the biggest audiences but I guess a fair share of this actually tune in because their very own club plays the top dog. More Leicester fans will watch Leicester vs. United than Leicester vs. Brighton. I assume the big clubs have done the necessary market research but I wouldn't put it past them to a) heavily overestimate their very own attraction to fans and b) heavily underestimate the effect of the backlash they're facing.
Also, consider the fact that the players might be excluded from WC, EC and CA. Messi, Ronaldo, Mbappe and Neymar can currently choose their clubs. For the first two it'll be their last shot at WC glory.