[1] "I think another possibility, and there our paper gives a little bit of evidence, is that if you have even one colleague who is remote, that yields about 30 percent of the loss from having everyone be remote." https://www.theatlantic.com/podcasts/archive/2024/06/remote-...
That rate will be lower than what they were paying for people living in the tech hubs (maybe in some cases actually 50%), but represent a major pay bump for people in the rest of the country. It's a win-win for everyone except the people who really want to stay in tech hubs.
Location agnostic pay comes close to what OP is suggesting: put your pay in the median of the country as a whole and pay that consistently to everyone regardless of where they live. The company saves money by not having to match tech hub prices, and there are tens of thousands of developers across the country who would love to accept a pay scale that's weighted higher than their local market by the tech hubs.