In 2011, there were 15 coaches with buyouts of more than $8M. In 2016, there were 33 coaches with buyouts that high, and that data only applies to the coaches at public universities. I imagine that Shaw, Helton, and Richt have buyouts exceeding that amount, and we already know that Kelly does. From what I can gather, some of the clauses are less "buyout" and more "you're gonna pay me the rest of the money owed on my contract." The coaches and, especially, their agents have really had the upper hand in contract negotiations of late. Harbaugh is getting paid $6M/year AND has a buyout of ~$25M.
Statistics and common sense indicate that there cannot possibly be ~40 coaches that deserve these buyout; there will be less turnover of head coaches in the coming years due to this development.
That Notre Dame snookered itself on a buyout clause after the Weis and Willingham fiascos beggars imagination.