The jump to the next PS are the 7nm and the CPU change.
If Sony matches 500$ price, it will just be the RX 480 Na'vi and 7nm sucessor, so we're speaking about 9TFLOPs, over a Fury X, which is a little worse than a GTX 1070. It's power won't be surprising, or at least it won't if they want to keep PS4 "noob" alive... But killing PS4 and not killing PS4 Pro should be hard to sell.
I think there's a possible way for both PS and Xbox:
Xbox One - Xbox One X - Xbox X [there One dies, One X stands]
PS4 - PS4 Pro - PS Pro [There PS4 dies, PS4 Pro stands]
They have to have thinked several ways to make this new two consoles paradigm painless and understandable for the masses. This could be one. And Ryzen based processors with 4 cores - 4 threads and "boost speed" for "future overclock" should be a good way to help One X / PS4 Pro to survive and then have a nice processor for 2020's consoles.
Uh, and if Sony matches 400$ price... It should be pretty close to One X in therms of power. I think Microsoft made a good movement here.
Edit: I used to wonder how should Microsoft make Xbox games boxes to help customers to difference games for Xbox One + One X and futurible One X only or One X + sucessor games... But this approach should solve the problem: Xbox One games boxes, Xbox X games boxes - PS4 games boxes, PS Pro boxes.
There's no way Sony launches PlayStation 5 in late 2019 with only a 9 Teraflop GPU. Regardless of how much a boost a new CPU will bring. It would just look bad from a marketing perspective, more so than a technical perspective (and technically, a 9TF GPU in PS5 won't be impressive). Waiting 2 years (after XB1X) to get 50% more power, when Microsoft did the same to PS4 Pro in just 1 year. Games running at 4K or anywhere near it, is still gonna chew up a large percentage of a 9 TFLOP GPU (it uses about 75% of a 6 TF GPU doing current-gen class graphics) so there wouldn't be enough left over for a generational leap beyond OG PS4, unless developers stuck with 1080p and no checker boarding to 4K or near it. PS5 GPU needs to be 12 TFLOP, minimum. Also, keep in mind, Cerny's comment about needing at least 8 TF GPU to render at native 4K without compromise, was referring to PS4 games, not next gen games in the early 2020s / PS5.