Stick with og PS5, it's the best console with the best value.

PCs have all of Microsoft's APIs and frameworks at their disposal and Nvidia/AMD/Intel doing the heavy lifting in compatibility and optimization with their drivers.

I suppose it might work for PlayStation if the CPU and memory are just about the same across platforms, closer even than the Xbox Series, but then just the GPU size alone (and PSU + cooling) might not create that sort of price gap between SKUs.

Plus development costs for the manufacturer make it even harder for such an idea to leave concept stage as you mentioned.

Consoles also have proprietary API's, albeit Sony's PS5 API is probably not as well-suited for scaling to the same extent DX12 is, since it is a single closed-platform. 

A lot of the extra processing would be eaten up in higher pixel-rates and framerates though, and the chipsets of the different SKUs likely will be using the same cores/compute units just with more or less of them and at different clock rates. A lot easier than DX12 having to work on very different architectures. 

Couldn't some developers just get lazy with the more powerful options if they didn't wanna bother supporting them though? Struggling with the Series S is natural since it's notably worse than the base model but as long as a game run ok enough on the mid-level option developers can just kinda ignore the higher tier ones if they want even if that would piss off the people who buy them.

For that scenario I'd personally remove the Series S tier one and have three options to keep it simpler and make things easier for developers and so games get held back less.

That would depend on the developer, but AFAIK on PC most set their performance targets at either the current or past generation of GPUs and then tend to work from top to bottom. The high-end is the first place where the game will run decently after all.

For the PS4 and PS4 Pro and Xbox One and Xbox One X they targeted the base models since that's what the vast majority of users had and then basically turned up the settings for the more powerful revisions. If I remember right Bloodborne is a notable case of a game that never got a PS4 Pro patch much to the annoyance of people who had the game and that console.

Sure, because the user base was there and most games were launched before the Pro (like Bloodborne) or started development with only PS4 devkits. No guarantee the cheapest model would be the best-selling one or what is the standard devkit in that scenario. The only guarantee is that the top models would run games better by default.

If the cheapest model is the same relative tier as the PS5 and Series X it's pretty clear it would be the best selling I'd say since Sony and Microsoft would push that model the most to build up an install base faster and for gaming higher tier hardware is notably less popular than cheaper options. The top 6 most popular GPU's in the Steam survey are all below 70 class after all. That model would seem good enough for most or at least a plurality of people basically.

This is a pretty interesting rundown. The 4070 still clears PS5 Pro's GPU performance in each category by some margin, but is still close. At least by comparing Sony's claims. The big unknown though being how performance will be impacted by PSSR since no one has had their hands on it. I still think it's highly unlikely Sony will be able to match at least DLSS since Nvidia has had multiple generations of refinement and added features, but that is one aspect I am very interested to see how well Sony is able to implement right off the bat.

The lack of a CPU upgrade though, will be a bottleneck down the line though. Same thing happened with last generations Pro consoles.

I think the problem is you seem to think that Sony is even attempting to do that. This product is for hardcore Sony fans. People invested in the ecosystem and always want the best of the best. Do you know that person who is constantly buying the new Iphone for absolutely no reason? That's who this is for. I guarantee they don't expect this to go far beyond 10% of overall console sales. It will also have the added benefit of getting more used PS5s into the wild so more people can get into the new gen without having to pay as much.