There is an excellent thread today at Slashdot about the problems faced by older, very experienced, and well-paid engineers. Although the thread is mostly about software engineers, it really applies to any 40yo+ people that think they will be able to stay working in the "tech trenches" their entire career.
I found this discussion very poignant because I am currently trying to get out of software engineering as my main profession once and for all.
Ask Slashdot: Am I Too Old To Learn New Programming Languages? - Slashdot