You might be interested in Quicksy or Snikket

Happy to answer any questions.

that one is not very popular, this one has 10x as many downloads: https://play.google.com/store/apps/details?id=eu.siacs.conversations

In what way has email centralized? Just because most users happen to be with one of a few players?

Except that most blogs still have feeds and the most popular XMPP client is on mobile?