Back when this article was written there were at least five or six Python frameworks, all competing. If Django ever starts sucking, I'm sure one of them, or a completely new one, will step up to take it's place. Ditto for Rails.
All part of the open-source circle of life :)
The Python web development community is very much divided into different, although largely cooperating, groups.
Django is definitely not the default choice when it comes to web development in Python and I doubt anyone seriously involved in the Django project would ever claim that.
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.