Looking at the GOR, Wake would own the broadcast and media rights of all of the teams that left. Wake would not get any revenue that the other teams were able to get from a new conference. However, those schools would not own the media and broadcast rights to their games, so they wouldn't bring new income to the new conference.
If 15 of the 16 teams decided to leave, it would probably happen by disbanding the conference which would likely invalidate some of the requirements of the GOR. ESPN would have to be on board with it, and at least 12 of the teams would have to vote to change the bylaws.
Just my opinion, I don't see anything happening until sometime close to 2036. Maybe a group of 3 super conferences is made. To make a change to the ACC, you would need ESPN and at least 12 members agreeing. The SEC doesn't have room for 12 new members, and ESPN isn't going to vote to strengthen the Big 10. The 2016 ACC GOR was implemented precisely to ensure that ACC teams were not picked away by other conferences. It is doing exactly what all of the ACC members intended for it to do when they signed it.