Not the OP, but I'm of similar age and also a mainframe programmer by trade. It's a pretty lucrative field to be into, especially because the businesses which operate mainframes tend to be very large and (mostly) stable corporations. While not as hip and cool as a Valley startup, there is something to being well paid and receiving good health and retirement benefits! =)

Those same corporations are also not blind to the fact that most of their COBOL workforce will be retiring, en mass, in the coming years, and are quite desperate to hire anyone willing to learn. My employer paid for me to attend a 3 month training program in order to learn how to use and develop on the IBM zSeries mainframe. It was a fantastic experience. As well, those same companies are looking to move as much of their COBOL code off of the mainframe and onto a distributed, server platform. While you can't beat the sheer power of Big Iron chugging along through a batch cycle, the CICS user interface leaves a lot to be desired. It's much more cost and time effective to build a web interface that talks to a Java middle-layer that lives on the mainframe (such that it can directly talk with DB2 or some such), compared to designing, building, and testing a CICS program to do the same thing, yet in a much more ugly fashion.