migrating from one framework to another in python
Your database queries(and object models), url config, and templates to say the least will all be specific to django. That said - if you understand what you're doing, recreating them in another package shouldn't take too long if you really need to at some later time.
edit: this is all assuming you dont integrate third party projects such as sqlalchemy and mako. Django plays nice with the builtins it ships with so it's often more trouble than its worth to use said modules.
I'm having trouble deciding which python framework to use for my website. So I've decided to bite the bullet and use Django. My question is how easy (or difficult) will it be to migrate to a different framework in future if I have issues with Django ?