The status of this clubs as the big dogs is being threatened by clubs that spend more money than what they can or are willing to spend. With this the number of potential future fans and share of the total football money pie in the future is potentially reduced for these clubs, losing fans to the likes of city and psg if they start to be constant protagonists in the CL. With functional FFP rules this would likely not have happened.
The fact that these clubs are run like a business is the problem. They don't spend absurd amounts of money because they need to be profitable, while the oil clubs don't care. In the case of Juventus it's not that the Angelli family doesn't have absurd money to spend, they just don't do it, at least not to the extent of city and psg. With functional FFP rules their status would not be threatened.
So no, it's not clear at all if this super league would be a thing if the clubs hierarchy wasn't at risk.