I don't buy it. This isn't the only mechanism, probably not even the most important one, for why salaries are where they are. Shortage of and especially of highly competent programmers is. In fact this actually underpins why jumping ship is even as easy as it is. Uninionization will provide additional leverage, while not diminishing the shortage pressure. Part of the point is that this leverage can substitute the leverage we have due to the current shortage, if and when it diminishes.