Didn't Sony said 33% of PS4 sales are Pro ? And at least in Quebec they disappear pretty quickly, seems to be selling just fine.
20% of total sales since it launched in November.
I think one thing these discussions needs to clarify when talking about the power uplift is whether people are using the Pro or the Base model as the power baseline.
Using the Base, going from 1.8TF to 10TF is a 5.5x power increase, using the Pro it's a 2.3 increase, essentially making the 'PS5' the same power step up as the Pro (at least in GPU terms - this doesn't include any benefits using Ryzen or custom components bring).
PS3 - PS4 was 4.5x uplift on GPU, so if Sony are using the Base model as their starting point for PS5, a 10TF machine in 2019 isn't an outside bet, and again CPU improvements driven by VR (something I've mentioned previously as being a potentially major design consideration for PS5) mean that even a 10TF console will be significantly more flexible in power for devs than the 2.3x over the Pro specs indicate.