Here's something I stumbled upon WRT to the election that extends the concept:

Rather, it is the views of those who have to maintain respectability in order to maintain their position that have changed. It is no longer permitted for them to even think the thoughts required to understand what just happened. The Overton Window has become the Overton Bubble.

From https://sydneytrads.com/2016/11/18/alistair-hermann/ which looks at it from the Australian viewpoint (i.e. I can't follow a lot of it ^_^ and haven't really tried to digest it yet).