It does give you reason for concern. But one thing jumps out at me, 15 years is a long time in the world of College Football. We all know the sport works in cycles and right know it is the SEC's turn at the top of that cycle. The question is what happens to ESPN when that cycle comes to an end? There is a reason that networks don't typically tie themselves that deeply with one conference. Because those cycles always come to an end.
Think of it this way, 15 years ago Nebraska was getting ready to win the first of back to back National Titles and the former Big 8 conference was in the midst of winning 4 titles in 8 years. They were the baddest boys on the block at the time. Who will be the big boys in 5, 10 or 15 years? ESPN is hoping it is still the SEC, but history says otherwise.
The SEC is in the midst of a tremendous run, but it is not unprecedented. The rules of attrition have always, and will always, apply to College Football.
BTW, ask the N.Y. Islanders how 15 year contracts work out. Had to get my required NHL shot in there.