Honestly, what I think you'll see is a movement back to the lower levels. These higher salaries in high COL areas will go away, simply because companies need to cut costs and the value of living in a big city is diminished.
This is one of the reasons International Paper moved to Memphis from the northeast in the 2000’s. The employees that were relocated couldn’t believe how much house they could buy in Memphis. I believe all those high salaried employees were offered retirement packages not long after the move.