I was semi-joking; but it is actually a serious question. (To the best of my understanding) a quantum-encrypted network provides rock-solid assurance that nobody is physically tapping your lines.
All quantum crypto gives you is one time pad material that cannot be derived from previous communications.
For example say you are able to record all classical communication between parties. If at some point in the future you are able to somehow compromise the initial encryption key you would be able to go back and decrypt any communications using this key and rotated keys based on the initial key or descendants of said keys if communicated within intercepted channel after the fact.
With quantum crypto there is no longer a physical linkage possible because pad data is guaranteed to be knowable to exactly two parties.
There is still very much a real classical problem in that you need to establish a trust relationship between yourself and your communication partner to have any assurance as to which party you are actually OTPing in quantum world...This is always done using an initial classical key to protect against Active MITM of the quantum channel.
While I appreciate the value in this scheme in the real world I do wonder what the actual benefit is for things like electric grid control cited in their paper where forward secrecy has very little value to begin with.
While it is true that a compromised key could not in theory be used for long....if you already had the ability to compromise current key you could then also perform an undetectable active MITM against the quantum communication channel and from then on be privy to all new OTP/key refreshes.
Any of us can exchange data over the Internet with the same level of assurances as the best fancy quantum gear...All you need to do is exchange OTP data offline (SD card filled with a few GB of random garbage) and you are set for a very long time of guaranteed intercept free communication. Years worth of voice chatter..lifetimes worth of text messages or short control messages all for small fractiones of pennies on the dollar. Sure it does not scale but no trust relationships ever really meaningfully do.
As with the quantum gear your vulnerability is and always shall be compromise of that which hold trust/keys.