It completely disables the communication pins and only allows power. Apple is not playing catch-up, all phones since the iPhone 5s (Fall 2013, receiving iOS 12

It completely disables the communication pins and only allows power. Apple is not playing catch-up, all phones since the iPhone 5s (Fall 2013, receiving iOS 12) have a hardware encryption key entangled with the user's passcode to decrypt data. The key is unique per phone, inaccessible to even the Secure Enclave firmware, and has PBKDF2 iterations tuned for 80ms per attempt. The Cellebrite attacks are getting closer to ~1s per attempt, and rely on being able to upload their own firmware to the phone. This feature looks to disable the last way of getting into iOS devices without the passcode. They certainly seem to be investing a lot in security.