>Apple could also push out an update tomorrow that would end this once and for all by utilizing device attestation and leveraging Secure Enclave, but this would potentially lock out older devices, something they were willing to do when they upgraded the FaceTime protocol a couple of years ago, but they might not want to do that this time around.

Just give it a couple more hardware generations to ensure the largest % of older hardware upgrades. Anything pre-secure enclave chip would need to be in the low digits I'm guessing. Then again, if they are going to block Messages, that might be the incentive to get these older device users to upgrade.