https://www.opengovasia.com/articles/8091-worlds-longest-unh...
The theory is sound and the technology is getting there. The question is really whether there's enough commercial interest. Joe Public doesn't care too much about this level of security, but governments, journalists, intelligence groups, and companies with a lot of intellectual property do.
I predict that there will be some commercial uptake of this tech in 20 or so years time, but I don't think it'll be that exciting in terms of practical application. It's already possible to be confident that the pure algorithm is secure, i.e. communications can't be read without some sort of social engineering, backdoors or the like.
Do you want pre-shared secrets and the expense of a quantum network to, in theory, have infinite security (in theory!), or are you okay with tried and tested RSA which gives you >1000000000 years security at a much cheaper cost, that actually works in practice?
Quantum mechanics allows for superdense coding, where you get a bit more than one bit per particle, but it's probably not really helpful.
If you could, high speed traders would not bother with microwave links.
Quantum networks are (in theory) impossible to snoop on without detection, so they are useful for distributing cryptographic keys. They might be useful to pass quantum states around between quantum computers if they're reliable enough.