Notably, such a design would still allow market forces to increase block rate/size during fee/block space demand increases, but even without miners turning off, which is cool.

I read that study a while back that discussed how incentives could become unstable in a fee-only scenario, with extra block re-orgs. There have probably been more studies since then. My analysis and research at the time pointed to that there seem to be various fee-smoothing mechanisms that are somewhat straightforward and could be implemented, but it also seems like not an existential risk and something that could be implemented if it starts being a problem. One of my opinions of the paper I read was that they didn’t sufficiently take into account economic incentives. Miners put serious capex into ASICS with long lifespans, and so even if block-by-block incentives can incentivize more re-orgs, the long term revenue comes from the reliability of the network. So it’s unclear that miners would cause enough block re-orgs to make the network stability shitty. But if that’s how it works out, there are fixes as you pointed out. Seems like something that can be done if it actually materializes as a problem one day, rather than something that needs to be done years or decades in advance of there *maybe* being a problem.