The current assumption is that every user has a single private key.
Cryptography based on elliptic curves often has better properties regarding performance and size, so it may be desirable for a user to use that instead of RSA. I do not think there is an immediate need to implement EC based public key crypto here, but the assumption of a single private key per use may hurt future adoption quite a lot.
There may be other reasons to maintain multiple private keys.
TLDR; please consider revising the assumption that a user has a single private key.
The current assumption is that every user has a single private key.
Cryptography based on elliptic curves often has better properties regarding performance and size, so it may be desirable for a user to use that instead of RSA. I do not think there is an immediate need to implement EC based public key crypto here, but the assumption of a single private key per use may hurt future adoption quite a lot.
There may be other reasons to maintain multiple private keys.
TLDR; please consider revising the assumption that a user has a single private key.