According to a Society for Human Resource Management report (no longer available as of 2019), 68% of human resource professionals have observed an increase in employees extending their planned retirement date due to the current economic conditions. This agrees with ExecuNet observations from their research, indicating that executives as of 2008 planned to retire at an average age of 76.9 (if health allows them to work that long, and finances allow for retirement even then). This is in contrast to 2006, when the average targeted age was 65.8.
Combining the above statistics with the fact that executive tenure in each job has been shrinking to as little as 1.5-2 years, an executive at 50 could easily have another 25 years of career left (nearly as much as he or she has accumulated thus far) and multiple remaining job changes.
I write executive resumes every day for clients who come to me at age 50 or 55 with the attitude that this next career move will probably be their last, and many express fears even at age 45 that they are losing their luster as a candidate due to age. The mindset that you are over the hill as far as your appeal in the job market at age 50 to 55 obviously needs to change. Continue to polish your skills and increase your knowledge, and shine up that executive resume for an extended stay in the world of work–and possibly several more challenging job experiences at different companies!