In the Starship #4 test flight (
) they had live video feed from liftoff through to both splashdowns. All the way through the plasma of very lengthy 'deorbiting'. That says a lot about the ability to communicate with hypersonic vehicles provided one owns a sufficient fleet of suitable comms satellites in orbit. For sure Starship has sufficient scale to provide lots of power, and some relatively benign locations on the unheated side. But as a very obvious demonstrator it is a sign of things to come. All the nations who either ar ealready, or may in due course become, part of AUKUS have an interest in hypersonics. Even if they have come to the conclusion they'd rather do it as a consortium than on their own.