Comment Switch to embedded (Score 2, Informative) 565
You'll find getting back into the field, to program in high level languages with all of your previous experience outdated, to be very difficult. Companies will not want to pay you the salary your years of experience would warrant, and it would be like starting over.
Instead, the method back in that I've found for those of us who started in the "old days" is to go for embedded systems development. The embedded world uses 10+ year old technologies, so your experience with assembly language programming and writing software for systems with limited amounts of RAM and storage space is a big plus for embedded systems development. There are plenty of companies still creating software for processors that run at between 4 and 20 MHz with anywhere from 256 bytes of RAM on up to a handful of kilobytes of RAM. I've found this sort of development work is much more interesting, anyway, and people with old school knowledge are considered more valuable, rather than a dinosaur, for such work.
Instead, the method back in that I've found for those of us who started in the "old days" is to go for embedded systems development. The embedded world uses 10+ year old technologies, so your experience with assembly language programming and writing software for systems with limited amounts of RAM and storage space is a big plus for embedded systems development. There are plenty of companies still creating software for processors that run at between 4 and 20 MHz with anywhere from 256 bytes of RAM on up to a handful of kilobytes of RAM. I've found this sort of development work is much more interesting, anyway, and people with old school knowledge are considered more valuable, rather than a dinosaur, for such work.