No chance on earth any breakaway league would just contain a small number like 12 teams mate though.
Is the list you state would be involved
If the ‘big six’ from the Premier League truly forced the issue, who could not see Real Madrid, Barcelona, PSG, Bayern Munich, Juventus and Inter Milan salivating at the idea of doing likewise to form at least a twelve-team “SuperLeague”.
could 100% add in AC Milan to that list, Athletico, Monaco, Dortmund for starters. maybe others such as Valencia, Seville, and othe rteams with either a historic large supporter base or who have had recent success etc.
They would also want some way of including at least one club from other major but lesser nations - Turkey, Netherlands, Portugal to capitalise on market audience, Galatasaray, Porto, Ajax for example, i also think as it'd be entirely about making more money you would see Celtic included in any breakaway - they have a massive worldwide supporter base, they won't miss out on bringing that into the competition. Maybe even a Russian team as well - a huge market and inclusion of a Russian team as with other nations makes it relevant to that country etc.
The effect it would have on the league should this happen - it would make it instantly more competitive, well in theory anyways, in reality you may just see 1 or 2 of the biggest clubs (such as us) dominate constantly.
The effect it would have on the calibre of the league - basically it would absolutely kill it, ALL top players would want to be playing in the new European league, the TV rights etc for the new league would shrink back to figures of 10 years ago, nearly every club left behind would be left in an absolute financial mess, and some would go under in Blackburn and Leeds style, including almost certainly us.
You'd then be left in a situation of any young player you developed or any breakthrough player you signed would be taken off you with ridiculous ease by any of the teams in the European league.
What SHOULD happen if they ever did do this, a permanent ban on the club EVER rejoining the league - so if this European super league goes tits up, then goodbye to all 7 of those clubs, and if you want to be kind to them - you make them rejoin in the lowest division of the leagues - so a good 4 years minimum and actually more as all 7 teams would be forced to compete for 1-2 promotion spots each year, any player who has been registered in this super league is ineligible to play in the domestic league - so no retirement home once the player gets used up and spat out by the 'big clubs'
The reality is that i don't think the English clubs actually want to do it, what they want is to give the impression they will do it, in order to receive a hugely more imbalanced share of the money the clubs each get, effectively cementing their place as a top 6 forever in essence.
Premier league should threaten back in terms of point deductions IF these clubs continue with the threats and talks over effectively destroying the competition which is giving them 100's millions per year to compete in it.