Agree with your thinking on this. FSU wants out no matter what and Clemson is definitely getting there. The ACC (and ESPN) know it is only a matter of time for them to get out. With ESPN getting pulled into the FSU lawsuit, it's in their best interest to get the situation settled and to make their cash cow (the SEC) happy.
I could see ESPN, the ACC, and the SEC negotiating to have not just FSU and Clemson, but UNC and UVA as well, to go into the SEC. The ACC gets a negotiated pay off for the loss of the 4 teams and a new media deal with ESPN at a lower value. If the ACC balks, ESPN notifies them the media deal will terminate in a couple of years and ESPN will not be interested in a renewal.