Is XMPP dead?
With ejabebr's latest release in april, XMPP Provides listing tens of them and snikket becoming a thing, i'd say no.
Yet every now and then someone on the fediverse comes and proclaims it's dead.
XMPP to me always sounded like an audio format or an x64 instruction extension. If you don’t already know what it is, I think most people would just gloss over it as “some nerd shit”. Which may or may not be desirable, depending on your perspective.