The Overton window isn't shifting. It's shattering.

Take gay marriage, for instance. There was a time when 95% (number made up, but I think it's roughly right) of the population thought that obviously gay marriage wasn't real marriage. There was a clearly defined window, and 95% of the population's position fit within 95% of the population's idea of what the window was.

Now you have maybe 40% of the population thinking that if you don't support gay marriage, you're a fascist oppressor and persecutor. You still have 30% thinking that no, gay marriage does not fit what marriage is. And you have the middle 30% thinking some variant of "they can marry, but you can question that without being a nazi". And each of those positions holds their own idea of where the Overton window is supposed to be.

In that landscape, there is no view of where the Overton window is that is 1) held by the majority of people and 2) the majority of people hold views that fit within that window. That's what I mean by the window shattering, not just moving.