Systems research is more relevant than ever. You should take a look over the papers published at conferences such as SOSP, OSDI, EuroSys and HotOS. You'll see quite a lot of papers from industry giants. Lots of research OSs are also gaining traction[1][2][3]. I'd say that we're moving towards specialization right now, with a specific OS architecture for your usecase. OS research is far more than Linux right now.
"MirageOS [40] is an OCaml-specific unikernel focusing
on type-safety, so does not support mainstream applications,
and its performance, as shown in our evaluation, is sub-par
with respect to other unikernel projects"