A few counter-points.
1) Scorpio,
taken within the context of the current Xbox One family, is likely going to offer a more compelling reason to upgrade than upgrading from a PS4 to a PS4 Pro. I touched on that here:
So to me, compared to the existing XBO's power level and feature set, Scorpio is likely going to appear as a dramatic upgrade and step-up from the XBO. (while still existing within the XBO family, which does complicate things) I don't think Scorpio will cause substantial fragmentation – VR is going to be the primary differentiator between the two – because the games/accessories/OS/etc. will all remain the same. How long the XBO is supported remains to be seen of course.
2) Within the Playstation family, in which the PS4 is already compatible with VR, the PS4 Pro seems like a much more marginal upgrade. Yes, it does offer graphical benefits for people who have 4K sets, HDTV sets, and VR headsets. But is there something there that makes your VR experience in particular so much better that warrants that upgrade? Considering they spent such a small amount of time on it, I'm not convinced.
I'm certainly not condemning Sony for this, but I think the raison d'etre for the PS4 Pro is fairly weak compared to the Scorpio
taken in context with the respective console families, the release windows, etc.