Rolling-releases of TrueOS have been available in beta form while the first official milestone is approaching. TrueOS will continue to be based on FreeBSD just as PC-BSD was all along. TrueOS is currently tracking the soon-to-be-released FreeBSD 11.0, but with some added changes.
The differences with FreeBSD 11.0 being advertised by TrueOS includes replacing OpenSSL with LibreSSl, making use of the Linux 4.7 kernel DRM compatibility layer for better Intel graphics support, and using pkg to manage the entire system -- including FreeBSD base.
TrueOS will be following a rolling-release model that tracks FreeBSD -CURRENT, the TrueOS desktop will be built around the project's Qt5-powered Lumina Desktop, etc.
Those wishing to learn more about the latest details on TrueOS can read today's evolution blog post.