Oracle Solaris is on life support because they don't have any of the old engineers. They have not worked on ZFS or DTrace since then (and the illumos community has massively improved those projects in the meantime). Recent news makes it look like Oracle Solaris may be killed quite soon.

That was the result, they tried to mistreat the OpenSolaris community and then Oracle no longer was competitive in the Solaris space.

If you want to learn more, check out bcantrill's talk. https://m.youtube.com/watch?v=-zRN7XLCRhc