Since I am bedridden and feverish aka not allowed to work on anything needing half a braincell, I want to throw my 2nd hat into the ring here
I think we need to look at this from different wants and aspects, I doubt there is no one good reason for doing a 5Pro, but maybe there are a lot of smaller ones that add up? With that said, I have firmly in the no pro camp, but would get one if it becomes reality.
Most people on here, who wants a 5Pro (or at least dream of a real NG console), want it to be as powerful as a PC with a 4090 in it, but that is of course not possible when you need to hit price and power/heat requirements. And like DF said, there is no AMD hardware that can do that anyway, so it looks like a waste of time and money for everybody.
Then there is the rumour/leak aspect where it basically says better RT and thats about it, by itself that is most likely not a big enough driver. Not that I belive 4K was a big driver for 4Pro, but that the market pitch was way easier that time. It does 4K and we moved on to debate wether it was good 4K or not and nobody really cared if it should exist or not.
Now, Sony, have the bottomline in mind, so if they could get away with making PS4.5 and call it 5Pro and sell it for twice the price they would. But logically that seems very farfetched and dumb of them to do.
But I think we all assume that Sony wants to shrink and do cost down as hard as possible and keep more cash/profit. Then again that might make it possible to price drop if needed due to how the market develops.
Looking back at the 4Pro, what was it? Just a bunch of more CUs and a bit more RAM, in the "butterfly design" to achieve it. Now if Sony could get a 5Pro for next to nothing in investment and create a half decent marketing pitch that the audience buys, maybe they could do a 5Pro for RT as mentioned in the leaks.
1. All PS5 drops to X nm, which by itself might not be worth the cost, but with less costly heatsink and maybe other components, then the current PS5 offering, is taken care off. And a price drop might be a manoeuvre that becomes available for Sony if needed in the future.
2. If we use the 4Pro template, minor adjustments in general, tacking on a bunch of CU/HW bits as a butterfly2ish (tm) soluition, where the extra hw bits could/might be Cerny RT acceleration patent implementation. Which are transparent to the games, you make an api call and if hw is there, it will be used, if it's not, then the computation is done in SW.
3. Sony still get to have the option of choice for the buyer, buy the new PS5 with optional disc adon or buy the more expensive 5Pro to get some nice god rays and more storage. But the psychology of price decoys are common, you put an expensive piece next to a less expensive piece to make the less expensive look like its a better value. And then you get the die hards/fanboys to get the expensive one. In nothing much changed in regards to perf (hey 4pro again), but Sony can rejuvenate their communication (make some new crazy commercials nobody understands etc), they get to write off the expenses across multiple projects/devices, hw contracts gets re-negotiated and their lineup is refreshed a bit.
Not sure how plausible this is, but big corp loves the word synergies so who knows.