I’m currently seeing a lot of arguments in the XMPP mailing lists about the future of OMEMO/whatever-its-name-will-be. There are disagreements on which encryption protocols to use, even I don’t have a completely clear idea of what that all is about, there is something about licences and interoperability… anyway what is clear to me is that the community (and the XSF itself) is not really stable on this yet (and it’s not really their fault actually), and I’m a bit worried about it.
In the end, I’ll probably go for OMEMO to be compatible with Conversations. It was even recently introduced into Smack so it might be easier than I think. The hard part will be the server side 
TL; DR: I’d like to close this for this year, but I don’t want to make any promises.