There may not be many “big and professional” operating system projects but, at the hobby level, it seems that there is a lot of interest in kernel dev actually.

HaikuOS, SerenityOS, Redox, and ReactOS are all going strong. The BSDs continue to advance as well. Redox is written in Rust even.

I believe Google sees Fuschia as a true Linux competitor.

When you say “we should just throw away the kernel entirely”, what are you suggesting?