SCENARIO #3: It goes to plaid.
So let's say everyone goes nuts and we get four 16-team leagues. Notre Dame would have to be one of the five Big Ten teams, because they would realize this is something they have to do whether they want to or not.
Even if the BIG EAST loses the minimum of two teams (plus Notre Dame), USF is going to be fine. In fact their lot in life will improve. There will be enough room in a 16-team ACC for the Bulls. Here, I'll show you.
BIG 16: Iowa, Minnesota, Wisconsin, Northwestern, Illinois, Indiana, Purdue, Notre Dame, Ohio State, Michigan, Michigan State, Penn State, Syracuse/Rutgers/Pittsburgh (2 of the 3), Nebraska, Missouri
SEC: Florida, Georgia, South Carolina, Tennessee, Kentucky, Vanderbilt, Alabama, Auburn, Ole Miss, Mississippi State, LSU, Arkansas, Texas, Texas A&M, Florida State/Louisville/Clemson/Georgia Tech (2 of the 4)
ACC: Miami, North Carolina, NC State, Duke, Virginia, Virginia Tech, Maryland, Wake Forest, Boston College, Connecticut, West Virginia, South Florida, Cincinnati, Florida State/Louisville/Clemson/Georgia Tech (the 2 that don't go to the SEC), Syracuse/Rutgers/Pittsburgh (the 1 that doesn't go to the Big 16)
PAC/WEST-16: Washington, Washington State, Oregon, Oregon State, California, Stanford, USC, UCLA, Arizona, Arizona State, Oklahoma, Oklahoma State, Kansas, Kansas State, Colorado, Texas Tech
If three or even four BIG EAST teams get sucked in by the Big Ten, it doesn't affect USF at all. In fact, it gives our three bachelorettes from the first set of scenarios a chance to be invited to the ACC, because that league would be either one or two teams short. And if you think they were catty and desperate before, just wait until they're fighting with each other for the last seat or two in the ACC life boat.
It's the weaker Big XII teams that really have to sweat it out if everyone goes to 16. The Big XII would be looted and pillaged by the SEC and Big 10, and unlike all the remaining BIG EAST teams, there would be too many of them left to be absorbed by the Pac-10. Weak sisters like Colorado, Baylor, Iowa State, and Texas Tech will be in big trouble in this scenario. The more Big XII teams are left after the SEC and Big 10 are done, the worse off those schools are. (Nebraska and Missouri would definitely be added to the new PAC/WEST-16 if they didn't go to the Big 10.) There's also nothing stopping this new league from replacing any of those vulnerable schools with Utah, TCU, Boise State, or BYU.
Even if there are open spots in the ACC, they're still in trouble. Does Lubbock, Texas, or Ames, Iowa, scream "Atlantic Coast Conference" to you?
Now then. The new ACC would be a big improvement for USF. They would have more natural rivals, including an in-state matchup with Miami and potentially with Florida State as well. The football would be an improvement - it would be the weakest of the four Godzilla conferences, but it's still better than the BIG EAST is now. They would remain in the best basketball league in the country. And of course they would have the prestige and swagger of being in a Godzilla conference, along with the big checks coming in.
The 16-team scenario is the best one for USF. It would be completely ridiculous for any conference to expand that much, and there's a good chance it would all go to crap eventually. But it's what you should be selfishly rooting for as a Bulls fan.