That most games will also be made with XSX in mind sure, that for like 2 years X1 will also be in mind sure. But for the rest of the gen if you think they will be tied to HDD you are sorely wrong, if they ever done that than the SSD was almost a pointless addition from both consoles.

Depends on the kind of chips they use. Unless that has been specified before and I missed it, the next part will explain why I think it will be more expensive.

For such a fast connection, I don't see Sony using TLC or QLC chips, but rather the more expensive MLC or even SLC or 3D XPoint. Microsoft on the other hand, could use TLC for their chips, which are much cheaper to produce than MLC, SLC or XPoint. There's also the (longshot) possibility that they use NOR memory instead of NAND, since that one is much faster than NAND on read and has a longer MTBF, but is much more expensive (2-3 times as much), less densely packed (50-80% extra size for the same capacity) and is somewhat slower at writing tasks.

Finally, the way it's connected and intertwined with the rest of the hardware could need a thicker PCB with more layers to work out correctly, and that can quickly drive up the prices.

You don't need parallel world. If you were here since gen 7 time you would have seem this flip several times.

It isn't even a factor of favoring faster SSD over faster CPU/GPU (except that most devs have been much more vocal about the SSD than the small difference in the CPU/GPU).

Your source to conclusion matches, but if you want better source listen to all devs, CGI, etc.

There are a few Japanese centric exclusive games nowadays for consoles and the number is getting smaller and smaller for Playstation. Japan moved to mobile platform for the most part.

Storage benefits more from parallel work than from better chips. More chips in parallel transfer more data than a faster single chip. Sonys solution might as well be a bunch of cheaper chips in parallel or fewer faster more expensive, we dont know. But we know the performance gain from the rchiter=cture is not speed alone as cerny said himself thaat its speed alone does not equate performance, there are many other factors boottlenecking the transfer and sony has removed thouse to. From the xbox side, we have not heard of such bottlenecks being removed, just that thanks to velocity archetecture they can comprese and decomprese textures more eficiently and that is the bigest chunk of data that needs to be streamed. So while ps5 read could maybe be sustained at 5.5gbs until MS clarifies, the xbox canot sustain that 2.4 gbs read. 

Yet those few will shine on ps5.

Honestly I would just expect developers to cater to the lowest common denominator. In this case expect both loading screens to adjust for slower SSDs in the XBX and lower graphics/resolutions to adjust for the PS5's lower power.

Though it will be easier to adjust for power than to adjust for loading screens and what not I believe, so maybe games will look a bit better on XBX but I do not think it would be a breaking point for most consumers

why does everything you say involves Forza rofl.. I am not a game dev, but even I know the architecture for driving games are way different, why are you using it as an example when we are obviously discussing about the potential for AAA open world games like GTA, Red Dead, Assassins Creed, Dark souls; etc...

I realize MS has released very few games the last several years so all you can bring up is Forza, but please try to use other points. 

It wont make much difference to third party games because probably devs will adjust the game based on XSX "limitation".
It's not that games will have an elevator in the xbox version, although the poorly PR prepared executive said that.
The difference will show on exclusives that sony will probably obligate them to make full use of it. Even then, in select exclusives. For a GT game for example there will be no difference.

Let's see what it means when it comes to the actual games then.