In addition to those specialties already mentioned, I'd add older databases and storage systems. Some quite large, quite critical codebases that do still need m

In addition to those specialties already mentioned, I'd add older databases and storage systems. Some quite large, quite critical codebases that do still need maintenance in their original language. There are also some organizations, e.g. Linux Foundation, with specific initiatives to support "critical infrastructure" code which is often in C.