You can never underestimate the power of a low price point. It helped PS2 sell over 155M units. My guess is the PS4 will be $199 by the time PS5 launches. Maybe even $179. And the Pro will be $299. The PS5 is probably going to be $150-$200 more than that. Budget shoppers will buy the PS4 or Pro, since they both will be supported for another 2-3 years after the PS5 launches.
This makes be believe the PS4 SS rumors even more so. There is little reason to mess with Pro as is for the next 3 years, if even continue selling it. I would think PS should be able to sell Pro at $299 as is and break even by now, but they likely need to get PS4 on 7nm and shrink it to get it down to $199 and have the hardware be somewhat profitable. So shrink PS4 this holiday and worry about a 7nm Pro later, if it's even necessary, since the $299-$399 market is already saturated, and especially if PS4 is just as compatible with the PS5 as Pro is. A super casual or poorer person simply won't care or be able to afford a Pro, since they couldn't afford PS4 before, so there would be little need to reduce the Pro price, if continue selling it period.
Unless they were to drop PS4 and shrink Pro to 7nm and offer a slim model for $249, which is possible but much less likely.
Worst case scenario, they could have future cross gen games set up so that if they play at 60fps to make sure that PS5 is able to use a worthy amount of it's potential, have Pro run at 1080p/60 and PS4 at 720p/60. This would also be a way to keep selling Pro at a reduced price, enticing existing PS4 owners to upgrade to Pro, if they didn't have the money for PS5, so they could at least remain playing at 1080p/60.