A simple system such as this will probably work OK, however, you should check to see what happens when the turn OFF sequence varies if the customer uses multiple remotes.

For example, I’ve been bitten in a system that was almost as simple: TV, A/V Receiver, Blu-ray, cable box. If one first turned OFF the TV, when the Blu-ray timed out and shut down, the cable box would turn ON the TV and select its input. Since I was using a control system, I could disable CEC and change the order of commands, this was not much of an issue, but it is a detail to check. Another annoyance is the cable box that updates in the middle of the night, then turns ON.