The Big East is wayyyy more likely to try to recobble the FB/BB model should the ACC implode than and anyone short of Notre Dame to a BB only league. There is simply no school even in the leagues expanded footprint that would add any value and I include a soon to be Mark Few-less Gonzaga.
BC/Cuse/Pitt/ Wake have zero value to the B1G, SEC or B12 and not much more to a ACC leftover conference (which would make UConn it's first call).
In a world where the B1G grabs UNC (with Duke), UVA (with VT), GATech; the SEC grabs Clemson/FSU while UL, NCST, Miami beg into the B12 or some combo thereof, ND rejoins the BE as a FB independent and a decision will have to be made especially if more that those 4 are leftover.
Does UConn bolt for a FB league with BC/Cuse/Pitt/Wake/Duke/UL/NCST or something like it? As of right now, I think the answer is a hard no. Better for UConn to split the FB schedule between those schools, the AAC, MAC, and FCS as a independent? The ACC defections would need to be limited to only the top FB schools to bring the total under 12. Every one of those schools would jump to join the BE assuming FB isn't going to be a factor.
A breakout FB division or a regional realignment of non-FB sports would facilitate such a move.
UConn would absolutely leave the Big East for an all sports league involving BC, Cuse, Pitt, Louisville... all former conference-mates where there was some semblance of rivalry with, plus Duke a blue-blood and filler. It's not much different than the current Big East or the Big East that existed or UConn expected to exist when it went to 1A.
The Big East schools might consider inviting the ACC remnants and reconstituting the hybrid model they loathed enough to leave... but it's more likely if there is going to be a hybrid conference that the rump-ACC picks and chooses which schools (if anything) from the Big East they want and leave the DePaul, Butler, etc crew behind. It's more likely that the rump-ACC chooses no basketball onlies and backfills from whatever's left out there with marginal value.... and UConn would still leave in that scenario.
From a hoops appeal scenario just swapping teams out:
BC replaces PC (local rival who hates UConn because of being passed by)
Cuse replaces St. John's (NY state rival)
Pitt replaces Villanova (Long-term opponent whose success at the same time as UConn made them a rival)
Louisville replaces Marquette (2004 add who had some success)
Duke replaces Creighton (Team that's been good, with whom UConn never shared a conference)
In fact, you could argue that the rump ACC has more attractive rivals/rivalries. They certainly have bigger brands meaning better content for TV/streaming services.