I have a question is this Zbrush 5 or has pixologic taken a Autodesk style yearly update schedule for now?
All releases going forward will be named using the release year. If more than one release happens in the same year then it would have a point number -- ZBrush 2018.1 for example.
Pixologic will continue with the same development philosophies and cadence that we've always had. The only thing changing is the switch to a numbering system that is less confusing for the general public. :)