A developer who picked up java ejb in 2000 at the age of 30 is now 40. How would your two cents count for this colleague?
There is an assumption that people over 40 are programming only mainframes. This is false.
I'm short of 50 by three years. I never wrote a stitch of cobol. 25 years ago I fixed on unix, data communications and C. Today, its linux, data communications and Java (not really a big jump).
To les infants: settle on a core technology for your career and be careful about investing too much in a knowledge domain that has a short shelf-life. If you have trouble deciding, remember the adage about entering the restaurant business: People will always have to eat.
Salutations from the Assisted Programming Home.