For cross-protocols messaging? Sure! But it has its flaws (for instance, only message bodies are encrypted, which makes XMPP’s OMEMO a superior solution in 1:1 and small groupchats). Also, it tackles only a small part of the problem, the larger picture (and problem) is about how the different protocols should inter-operate (exchange handshakes, keys, …), and this is nowhere near ready yet: https://datatracker.ietf.org/wg/mimi/about/