Me too, I'm convinced it has a place - the number of single file projects over the past few years can't be a coincidence.

For me the two missing pieces were models and a path to migrate to a full project once it outgrew a single file, so I wrote nanodjango (https://github.com/radiac/nanodjango/, formerly django-flasky) - you can use the ORM and admin site, and I recently added a "convert" command to automatically break up a single page app into a full Django project structure.

I've been using it for a couple of years for prototyping/experimenting and putting together small apps, and with the new features this year feels like it's a really practical alternative to flask.