Personally I don't think so wrt frame. The bike handles well, both on road and track so I'm not convinced Ducati will want to add weight. They seem to have more of a handle now in wsbk as well. I think Ducati would view Moto GP separately given the difference in power, grip, materials etc used in prototype machines.
The V4... I remember when the 1199 was released Bayliss saying the thing he was most proud of was that it had 2 cylinders. Implies that they considered the V4 then, you'd probably expect them to produce something in the future, it moves away from their identity though with twins.