A number of large law firms have sent their staff to low-compensation areas. Littler opened a staff facility in Kansas City (was San Francisco). Orrick was the leader, almost 20 years ago they moved staff to West Virginia. Someone brought it up when I was with a Detroit firm, but it was pointed out that Detroit was already a low-compensation area, heh heh heh.
Not uncommon at all. And now that employees can literally be anywhere, I expect more of this. My son told me his SF apartment rent dropped about 20%.