Subkeys are definitely important. However, I believe there are already NIPs addressing that.

Dismissing something as a joke at such an early stage, especially when the problem is recognized and being worked on, is foolish. 

 James is a high level cryptographer. I take it with a grain of salt. The cryptography is primary for him. 

 Highly specialized people sometimes miss the bigger picture 😉 Either way, he will eventually get what he wants.