I don't know if the purpose with Key is to compete with the major password managers or not.
If it is, I think Key should have support for YubiKey, like LastPass and KeyPass etc have.
YubiKey may be the next big thing in 2-factor authentication, and is an excellent solution combined with a password manager product, a hardware + software authentication. For example Facebook and Google employees are now testing this and if all goes well we'll might soon see them offering YubiKey support to their customers. That would be huge!