Simply put I don’t think there’s any way at all that they could be allowed to coexist. It would be completely farcical to award CL places as though the 6 seceding clubs don’t exist, it makes the league table and the basic unity of the competition a complete joke.
Edit to say that this leads inescapably to the conclusion that IF (IF IF IF) the ESL is actually established there is no other option but to eject the participants from the league. It would be utterly catastrophic for the leagues but I don’t see any other way around it.