There are plenty of tech companies paying great salaries in the bay because they have to, otherwise they would just go work for someone else. On the other hand, if you lived in Oklahoma you aren't going to say no to $LOCAL_OFFER+10k just because bay area salaries are $LOCAL_OFFER+90k.
As long as this disparity exists, I forsee bay area salaries and CoL still being high. Until companies move headquarters out of the bay, the trend will continue.