There isn’t really a reason why replacing the True Depth sensors should be a “common replacement” like the home button was. The home button had to be replaced because it was a physical piece of hardware that was pressed millions of times before failing. The True Depth sensor should fail rarely since it is protected under glass and won’t be hammered on constantly.
Absolutely! It'd be great if the the pencil could ping back its location using GPS, or cellular, or WiFi, or...wait we have low power bluetooth...hmm, I guess it could tell us if we are in the same 15 foot radius.