One of the developers here:
Yes, the Keyring reimplementation is in progress and ends very soon. After the redesign, applications built on top of E2E library will be able to use different sources of both public and private keys (so it's easy to do integrations with GnuPG, hardware keys HKP, or e.g. Facebook).
The API will be similar to what's in https://github.com/google/end-to-end/wiki/Keyring.