Nothing will save django for free because if you used that your most likely real problem is scaling postgres or mysql.

Use as many appservers as your customer base will pay you for.

Basically, cry in your beer because you're so rich and successful now that the framework won't handle your stuff.

Agreed. Scaling Django isn't difficult really. Just spin up another instance if you need to. The major problem is scaling the DB. Making sure you're not bogging Postgres down by making it have to deal with possible race conditions is difficult.

Why would you prefer to depend on this (Japronto), instead of Gunicorn or uWSGI?

I don't thing for now those are comparable, uWsgi is a LOT more than what a 0.1 release is.

uWSGI has very decent HTTP/1.1 performance

http://uwsgi-docs.readthedocs.io/en/latest/HTTP.html