Well, yes, you can convert subDs to Nurbs in Fusion… but so can T-Spline for Rhino, or Inventor, any other incarnation of T-spline and even Maya can convert entire polygon objects to nurbs. Doesn’t even Modo have some plug in to do that?
The advantage of Fusion is of course that you can have the conversion within the modelling process in the timeline and can always go back to your subD and make changes after the fact.
But what you also need to be aware of is that converted SubDs are not “clean” or “perfect” at all and quite the opposite of single span Class A modelling. The math of these surfaces is REALLY heavy. Yes, you can thicken them, etc. But it sounds much more useful than it is in reality cause they are so friggin overdefined and complicated that they break at every chance they get when you start building upon them and do things that go beyond a simple thicken of the surface. The SubDs can be a quick solution and sometimes are the easiest way out of a problem, but they are usually always the least elegant solution.
I really like the idea of what Fusion is trying to do with SubDs/T-Splines… but it is just not really finished and useful yet and almost creates as many problems as it solves, from a technical standpoint.