Will changing old apple ID email still allow old itunes music purchases permissions?

I have an old apple ID that is connected to an old email that I don't have access to and which will soon be deactivated. I do have access to my old apple ID account still, this old apple ID is also connected to several hundred $$$ of itunes music purchases that I don't ever want to lose.

If I change my old apple ID to connect to a different email (but per my reading it is still the same apple account), will I still have access/permission to use the old itunes music purchases in the future?

Thank you!

Calder