I don't think all of those teams would get scooped up by the remaining 3 power leagues. There's a reason the ACC is not a valuable league.
FSU, Clemson, Miami, UNC, UVA, and VT are definitely finding homes. ND too, if they want one.
Pitt, NCSU, Duke, and Louisville maybe but not guaranteed. I don't think all four get invites.
Wake, BC, GT, Syracuse - not happening.
I'd bet about 6 of the original 15 plus the three new ones do not get a P3 invite.
It's not an outlandish possibility that the Big East reconstitutes its 90s-early 2000s model.