[jerf]

AIUI, this sort of system is likely to end up a lot like TLS negotiation and asymmetric crypto in general. Even if it never has very much bandwidth, the ability to share secrets on a channel that is not just declared secure by engineers, but declared secure by physics has some advantages. Asymmetric crypto is generally atrociously slow too, but incredible useful because we can use it to bootstrap symmetric crypto which is very fast.

Of course, if it does upgrade to the point that it can move gigabits per second, they'll use it for that. I don't know of a particular reason why this would be fundamentally impossible. I'm just saying that's not a necessary condition for the technology to be useful.