[isotropy]

Quantum key distribution solves the sharing problem and will arrive sooner, for a certain budget.

[pclmulqdq]

I'm not so sure - QKD needs good SNR optical paths from source to destination, so over any real distance it's pretty hard. Physical medium security is just a matter of money today.

There are ideas of satellites doing QKD, but that will fall firmly into the realm of nation-states, which already spend a shit load on physical security.