django id integer limit
Adding this as an answer.  Django maps this to serial columns which means that the maximum value is in the 2 billion range ( 2,147,483,647 to be exact).  While that is unlikely to be an issue for most applications, if you do, you could alter the type to become a bigint instead and this would make it highly unlikely you will ever reach the end of 64-bit int space.
Is there a limit to the AutoField in a Django model or the database back-ends?
The Django project I am working on could potentially see a lot of objects in certain database tables which would be in excess of 40000 within a short amount of time.
I am using Sqlite for dev and Postgresql for production.