[didip]

Observing older programmers within my circle, they tend to master a few specialized skills that's hard to get from the hardcore and enthusiastic 20+.

There are a lot of subdomains within programming. Mastering things like Unix tools, patching certain web servers, knowing the kinks of specific RDBMS and/or filesystem, how to design batch processing, makes you a lot harder to be replaced by those 20+.

Not all 20+ guys are hacking on PyPy or Firefox. Most of them are Rails/PHP warriors. Competing against them is a lot easier if you master skills that can only be obtained by experience.

[jacquesm]

Don't rule out the embedded world either. Lots of gray hair there.