The SF salary is high because of high demand and low supply (of competent engineers). If you move remote, you increase the supply of competent engineers (there are likely people in middle-of-nowhere that are just as good as SF engineers but don't want to move because of other reasons - hence market inefficiency). Since you're increasing supply with the same demand, now the SF salary is going to drop (and establish a new market clearing price with the new supply & demand dynamics).
I think in the long run the SF salary (for the average developer) will be a historical anomaly in a place and time - kind of like the California Gold Rush in the 19th century.
(If your argument boils down to SF having more strictly more competent engineers than other places and that being the cause of the pay discrepancy, I strongly disagree)
Google has problems money can't solve as a company. I personally won't, and I coach juniors to stay away from many of the big names purely because of their toxic influence in the tech sector. They are of course free to do as they like, but I have an alright success rate with getting people to pass on those jobs to do something somewhat more constructive elsewhere.
It's like Fintech; a black hole of talent away from actually important work that needs to be done. You get that much capital condensed under one company, and it starts to channel itself against overall societal interests as it seeks to ensure it's own survival distributed across jurisdictions, fueled more by ignoramt adherence to past performance predicts future results amongst the capital management class implicitly picking winners through retarded capital overvaluations through overly aggressive M&A's and purging of the competitive landscape.
