Right now no regular user has the technical ability to fiddle with a phone's laminated screen glued to a touch matrix paired with a fingerprint sensor and a camera, so we're alreay past the complexity threshold.

But we could still reuse a screen block from phone A on phone B, except that's been forbidden by technical measures specially added to prevent it.

The same way we could probably replace a whole leg with another from a robot from the same series, except it will be DRMed to death.

We'll have to eternally push for regulation I think, companies will always try their best to fuck with repairability.