I wish Sony and/or MS share this thought. They could even open up Pro/X for games that no longer have to run on the base models as well. I doubt this happens, but it would be more fair to the customers and limits the risk to change vendor.What I mean by that is: I strongly believe the kind of gamer-Joe that waits untill the time ps5 is reaching $299 to buy it, would still not buy it at launch even if there was a $299 sku available then. This dude simply is not in a rush to buy the new cutting edge toy. He'd rather wait for the thing to get more must-have software and hope they drop the price further to motivate him even more.
The question 'can we assume GPU requirements to scale with screen pixels?' is a difficult one. It's easy to say yes looking at current games, but it changes when thinking about promising tech like variable rate shading or object space shading.
If there is a 1:4 ratio for HD vs 4K, those techniques become less attractive to progress. So i would want something like 1:2.5 maybe, which appears a bit extreme, but 1:3 is quite a big difference already.
In general i do not like different console models already at launch. Too confusing, too much danger of splitting people into first and secondary class gamers. Risk of lazy optimization. Fragmentation and destabilization of a market that won't grow anymore in any case i guess.
A weak streaming console might make sense, but otherwise HD vs. 4K alone does not justify different specs. Targeting 1440p and upscale / checkerboard is good enough. Focus has to be mostly on better games anyways.