The premier league doesn’t have the power to send them to the 7th division thanks to being a breakaway league. They can relegate them, or they can expel them from the premier league.
If they choose to expel them then Man City would have to apply to the EFL to join that league system (which the EFL would almost certainly accept due to the revenue boost they’d see) and at that point the EFL would decide if they join either the Champ, Lg1 or Lg2.
If by some magic the EFL also rejected them, then they would have to apply to whatever governing body runs the two vanarama tiers or even lower.
The premier league doesn’t have the power to send them to the 7th division thanks to being a breakaway league. They can relegate them, or they can expel them from the premier league.
If they choose to expel them then Man City would have to apply to the EFL to join that league system (which the EFL would almost certainly accept due to the revenue boost they’d see) and at that point the EFL would decide if they join either the Champ, Lg1 or Lg2.
If by some magic the EFL also rejected them, then they would have to apply to whatever governing body runs the two vanarama tiers or even lower.