Well, in their FAQ the Matrix team states that they love both IRC and XMPP and that for those whom these options perform better they wish the best of luck continuing to use them. Matrix does have some qualities they do not and they do not mean to compete with them, rather to put up bridges so as to federate between these decentralized protocols.
Personally, I want to move away from communicating through Discord with many of my friends. I do not believe neither IRC nor XMPP would entice them, but Matrix could as soon as they finish implementing their new video call capabilities. The same goes for community projects that use Discord as a replacement for forums.