Once we move to next gen games proper we will see more 30fps only games. Devs will want to see what can they do with those CPUs and GPUs.
Not sure what will that change, there are already plenty of pretty good reconstruction methods on consoles.
We know that there is a mode that runs at 30fps, we dont know about the existence of another mode that runs at 60, we didnt know about Ratchet's 60fps mode until a famitsu interview dropped.
AMD's TSR, which is featured in Unreal 5, apparently scales games from 1080p to 4k, which is quite a bit more than traditional reconstruction or checkerboarding techniques do (typically 2x, or 1440p-4k).
I have to imagine thier multi-engine solution FSR will be similar. If the technique works well enough, it's possible we may even see it used to upscale images from resolutions lower than 1080p. So perhaps if a next-gen game runs at a native 1440p 30, we could see 60fps modes reconstructed from 900p 60fps, 720, or even 540p.
That could mean that devs should never really be bottlnecked, unless they use an absurd amount of CPU power (or don't have time to optimized 16-threads).