Guilty SPARC: Oracle euthanizes Solaris 12, expunging it from roadmap "Solaris 11.next" projected to arrive in late 2018, is last version through 2021. Sean Gallagher – Jan 18, 2017 12 ...

What I think is happening is that Solaris 11.next, the Solaris 12 replacement, will be the long-term support version for Solaris. In short, it will get security and other necessary patches, ...

Instead, Oracle replaced Solaris 12 on its product roadmap with something called Solaris 11.next. There is also reference to SPARC next and SPARC next+.

Oracle has announced the availability of Oracle Solaris Studio 12.3, a C, C++, and Fortran development platform for building fast, scalable enterprise applications for Oracle Solaris systems.