Is it possible to convert a Wordpress theme to a flat HTML or Django template?
That's actually the most straight-forward way to port any theme from one platform to another. Create a single page/post/whatever with clearly defined placeholders in the text: [Title] [Content] [Author Name] and so on. Then copy the source HTML into your favorite text or code editor and begin adding in the code specific to the platform you want to deploy the theme on.
I've seen this done very well when taking themes from one platform into WordPress. It should work just as well taking them out of WordPress, too. Just be prepared to invest a lot of work in rebuilding the usability on the administrative back-end of things.