I lead a PL/VMs/compilers research group and the number of organisations interested in hiring people in this area keeps growing and growing. Now, that's not to say that there are ever going to be hundreds of thousands people working in this field, but it turns out that lots of organisations have realised they have pressing language needs. It varies all the way from those wanting to make mainstream language implementations perform better on their codebases to those wanting to reimplement a major internal language in a modern fashion.

At the moment -- and I expect for the foreseeable future -- demand quite significantly outstrips supply. Because of that, organisations are often quite flexible in how they view potential hires in this area. Simplifying a bit, there are two main ways to get in to the field: obtain specific training in the field (e.g. a PhD); start / contribute to a project (not necessarily OSS) that shows expertise (e.g. if you start filing high quality PRs against Rust or LLVM, people will fairly quickly realise you know what you're doing).

Best of luck -- it's a really fun field, with lots of interesting challenges, and a good group of people!