Flask - What happens when secret key is lost?

There is a current ticket open on documenting exactly this question: https://code.djangoproject.com/ticket/22310. I'd worked through most of it but somehow lost my changes.

From memory, and without review by a second pair of eyes, I believe the effects are limited to:
- All currently existing sessions are invalidated.
- All password reset tokens are invalidated.
- All form previews in progress require an additional confirmation.
- All form wizards in progress are reset, and if using the cookie backend for form wizards, this may lead to exceptions.

Also, any third party packages or any of your own code that uses the secret key may be affected. Notably not affected (in Django itself) are user passwords, and general content in the database.