This used to be a firing offense!

If you put in code on the off chance that memory might grow, or that a "feature" might be needed in the next revision, you're looking for trouble. The next rev just might be on a different MCU.

Aside from that, how can you ensure that the code won't be executed? Yes, you can simulate it. However, unless you test the circuit quite rigorously, stimulating all the inputs in random sequence, and automatically observing the response, you'll never be certain. The old saw was and is, "When in doubt, leave it out!"

Likewise, if you include support in the hardware for things not required in the objective spec's, well, see you down at the unemployment office!

RE