As a user who has watched development on this and several other projects: I doubt it. I haven’t seen any hints that it is, then again, I haven’t parsed the entirety of the forums and site here. Although Pixologic is the only one that can answer definitively - they probably wont give an answer as doing so would probably cause a lot of casual artists to stop checking in. They’re hoping that if casual artists keep checking in, they’ll see the features in zBrush and if they ever stop being causal artists and start doing this for money, they might invest in zBrush as a tool.
Points against it continuing development: Scupltris has become pretty unnecessary at the moment. Even tools like Blender are incorporating similar functionality, and have a far larger support base. Blender has an insane learning curve for anyone just getting into this sort of thing - which is a point in sculptris’ favor because scuptris feels natural and is easy to use. Then again, just try to wrap your head around Maya or Zbrush without watching a lot of tutorials. Also there are issues with the meshes that Sculptris produces, which when you bring them into other applications require either extreme decimation before export or a lot of optimization once you’re in your target app - or both. Finally, Scuptris’ feature set might get incorporated directly into zBrush when they work out the tessellation issues (triangles bad for geometry, so you need a geometry cleaner in the system which adds a lot of processing weight to the subsystem. It depends if better geometry algorithms crop up in the future.).
Had the project remained semi-open or gone full open-source it would have garnered some community support and input plus if the developer lost the edge on it someone might have forked it or picked it up. Seriously, though, lots of projects like this one fizzle and die. I think there’s a lot of utility for an app that just does one thing really well. But, I think what the sculptris designer was looking for was to show of his skills at developing an application of this nature, and get picked up by a software company like Pixologic. A steady source of income or food on the table is always a number one priority. You can’t develop good software for people if you’re starving to death. I don’t blame the dev for taking that route. He gave us an amazing tool that is still usable even if it is losing its relevance. We got it for free and it got him a job.
Its still on my desktop, but with all the other tools, its lost a bit of its shine.