Thats probably true, but this is where the negotiations come in.
The Super League has said they'll scale solidarity money with revenue growth, so this is where the PL clubs need to say, "well you've all committed to 23 years of this, now we are going to need you to legally commit to our slice, and failure to provide that will result in your expulsion".
Theres so much further to go here and a lot of potential for the super league to make this appetising enough for people to swallow.
They want the CL to still run alongside their competition for example - if winning the CL got you a 5 year membership of the super league, wouldn't that completely undercut most of the objections about "taking away the dream?"
They have announced basically their bottom line - security for 15 founding clubs, more games, taking control of the organisation away from UEFA. Everything else is negotiable.
A few things:
If I'm the league, in a perfect world, I only accept that scale with a guaranteed minimum with escalators plus a kicker that floats with Super League revenue.
The Super League needs the domestic league presence -- today -- because fans of Super League clubs want to support sides that win matches, which is no guarantee in the Super League. They need to cement the fan bases.
Once the Super League is an established entity, with the "open slots" filled with the most reliable revenue producers (which may mean keeping an open slot or two, but I doubt it), the Super League will close up shop, because their members will have revenue sharing of some sort, all the best sides, an optimized distribution stream, unified branding/marketing -- all the things it takes time for a start-up to put together.
Thus the leagues are mere step ladders -- and its members are cannon fodder. At some point the Super League owners won't care if their sides win or lose the Super League, as long as they are making an effective guaranteed return.
As I think you've noted (others have) expulsion isn't a threat. It's ultimately what the Super League sides want; they just aren't ready yet. And they figure demand is set to explode post-pandemic, and several of these clubs need money now. Hence the timing of this intermediate "CL-ish" step before the breakaway league is truly "ready", and the current reliance on the domestic leagues, which I believe is nothing like permanent.
Re the dream -- no, I think that issue is kind of all or nothing. While technically not just any side can earn a spot in Europe, theoretically they can. Officially locking in any European slot (let alone 15 of them) regardless of the pragmatic lock-ups some clubs have is still going to be perceived as a dream-destroyer, and I can see why.