Less pay for staying in the job?
While I kind of agree with the conclusion, the analysis has problems. Changing jobs doesn't cause higher pay, it's the other way around: if you find a better job than the one you have, you leave, and if you don't you stay.
A good takeaway, though, is to keep half an eye on the market for your skills and experience. Update your resume frequently. Search for jobs even when you're not really looking for one. For bonus points, even apply at some of these jobs - keep your interview skills sharp, see the kinds of questions people are asking, and maybe even unexpectedly get an offer you'd be thrilled to accept.