Minneapolis springs immediately to mind. Companies like Amazon are opening dev offices in medium-sized American cities now as well, because importing everyone into Seattle or Boston isn't sustainable. From my experiences in places like Minneapolis and Cincinnati, I'd project a pretty serious difussion of tech talent back into the Midwest.
I've interviewed with "tech" companies in some of the cities you mentioned. The compensation was substantially lower than anything I can get in the Bay Area (by about a factor of 2 compared to my current compensation, for example). The CoL adjustment wouldn't be greater than the reduced savings rate.
These companies need to realize that the market rate for the kinds of engineering and talent they demand is set in the bigger cities, not their little slice of the Midwest. I understand why they're doing it, but for all the issues in the Bay Area the opportunities are still better than almost anywhere else and so is the pay.
Amazon does have 29 positions open in Minneapolis. On the other hand, they have 187 positions in Palo Alto plus 185 in San Francisco. And 7260 in Seattle.