In this demo I show you how you can still use the infrared remote from the 3rd generation Apple tv on the new 4th generation Apple tv. You will still have the ability to move left, right, up, down, select an item, choose menu, and use play/pause. You don't have access to either the Siri button or Home buttons of course, and to state the obvious, no touch trackpad.
I did not have to do any special setup to use the old infrared remote.