So what exactly is the status of Element X? I was under the impression it's still in development, lacking some features of the old app, and will fully replace it when it's ready.

If I search for Element on app stores I still get the old app first (with millions of installs, vs. tens of thousands with Element X), and https://matrix.org/try-matrix also still points people to the old app. So I'm confused what "past" you're talking about :)

Similar situation with Dendrite BTW, it's been in beta forever, and the only private Matrix community I ever was a part of ditched it because Synapse was too much of a resource hog, and there's no clear migration path.