What are you talking about? BSD sees plenty of use, for its support of zfs, dtrace, and jails alone.
Unless you're heavily invested in the Linux kernel and Linux-only tech, I'd advise to keep your software running on the BSDs as well as Linux to avoid monocultures in your own best interest. The strength of F/OSS is in giving you choice, eg. by providing two (or more) interchangeable, excellent O/S's and compiler suites.