........... I hope they don't change this lens......
Why on earth would you hope they don't change this lens?
If you have this excellent lens and are happy with it - fine.
But a lot of people would really like a lightweight 400 prime lens with IS to allow them to shoot fast moving objects at say 100 ISO. This is not possible with the current lens which is why the slightly inferior 100-400 L IS lens is so popular.
If Canon had your attitude there would be no IS lenses at all!