If your concern is job security, learn COBOL. If you want to become a better programmer, to be flexible enough to write whatever software needs to be written o

If your concern is job security, learn COBOL. If you want to become a better programmer, to be flexible enough to write whatever software needs to be written over the next couple of decades, then diversity is important. Learn a Lisp. Learn a scripting language like Perl. Learn something low-level, like C or C++. Learn a line of business language like Java or C#. Most software doesn't require mastery of a specific language, and having a broad background will mean you can adapt to whatever the future decides is 'in'. Learn a bit of everything. Edit: Don't learn COBOL.