That's less true for the top 20% or so of tech candidates. A person with known skills and a good network can obtain offers from multiple remote-friendly companies today. There's already a location-ignorant market for their skills (probably not at San Francisco comp, but also not at rural North Dakota comp).
As more remote jobs are available, more people will receive multiple remote offers, that is, they'll find a deeper location-ignorant market for their skills. Over time, one would expect this location-ignorant comp to settle around the actual value added.
(Longer explanation in a related thread: https://news.ycombinator.com/item?id=18900072#18903795)
so you couldn't do this without either updating with HR or tax fraud
Hopefully if enough companies start hiring remote workers, our leverage will go up.
If remote work were to go mainstream and that became the norm, employers won't pay different salaries based on location: they will pay one salary based on the cheapest location. It's not that different from outsourcing work today — there might exist manufacturing workers in the Rust belt that are capable of doing manufacturing, but employers just shift all their supply chains out to cheaper countries, since there's little difference between a Chinese person's labor, and a Pennsylvanian's labor.
Similarly, if everyone is remote, then the difference between employees that live in low COL areas and employees that live in high COL areas starts to really blur. There might be exceptions to this for extremely high skilled engineers, but they're marginal cases.
If we move to an all-remote (or even a "most-remote") engineering culture, then software engineering jobs will simply be "outsourced" to the cheapest COL areas.
This "good talent" is not the norm. Google has tens of thousands of software engineers, and only a handful of them (mostly the staff/principal/distinguished engineers) have the kind of negotiation leverage you're talking about, but they already get paid a lot in high COL cities anyway.
I think today a lot of “good but not top” talent find themselves crammed into the very crowded Bay Area. I’m hopeful that can be relieved a bit. But I’m being pretty optimistic.
They don't have to pay more in cheaper areas to attract candidates, so they don't.
I took a substantial paycut at Google when I transferred from the US to Germany, for example, even though I was doing essentially the same work.
Other factors are at play than pure rational economics, though, so that might or might not work out.