That’s the idea currently, yes. The SubD ‘test’ command would only be available in the WIPs.
Just so that I understand what you are saying - are you using that command currently? I’ve just gone through all your posts that contain the word SubD and cannot really tell if you are actively using this for something. Other than conversion from SubD cages that are produced in an other application, that is. That might possibly be enough to warrant the continuation of the command in the released RH6 version - I dunno.
… and I guess that is 3 year from the point where more work is done on the SubD engine in Rhino…