Earlier quoted context omitted.
> Oracle does maintain Solaris, which would seem to me to entail a much larger support burden than Red Hat's stewardship of their enterprise Linux distribution. Solaris was effectively killed off in 2017 when Oracle laid off most people working on it. And Open Solaris is dead too.
Illumos also effectively died when most of their corporate support switched to Linux. Had nothing to do with Oracle. That said, I believe OpenIndiana is still being maintained, but their release cycle is rather slow.
Rumours of our death are, as ever, greatly exaggerated. We continue to maintain the core OS facilities provided by illumos and the organisations behind distributions like SmartOS and OmniOS continue to ship maintained, supported software to a mixture of community and commercial users.