You sure about that? It is my understanding that Zope/Plone has a fairly sizable community. They're just not as loud on the web as other framework fans. No one will know for sure until they are all counted though.
I would love to see a scientifically exact census but I don't think it can be done. Maybe PyPI could roughly tell the story? But you won't get a real unique-users count unless your logging identifies unique users, who wants that?
Please understand: I am not a big Django promoter, I disagree with many of its design principles, and I don't think that other things are "dead". I know that there are reasonable numbers of people out there using Zope/Plone, Flask, Pyramid, and other things. Just because Django is huge doesn't mean they are nothing or not worth looking at. I believe Rails is significantly bigger than Django, but that doesn't mean I'm switching to Rails.