Some people like slack or telegram because they provide an API for BOTs. Something IRC has been open to since the begining.
Non power users might have trouble using IRC with the usual clients (mIRC/irssi/bitchx).
Today a family member, not technical and 60+yrs asked about "that tool" that is like whatsapp however it allows users that just joined a group to read old messages. He was referring to slack. He wanted to create a group and when new users from his company joined, they would be able to read whatever was written on that group.
So with this in mind, i think what would really work (also) is to have something on the front of IRC (some bouncer) with a pretty UI that logs everything and allows new users to connect via mobile, standard irc clients, and also send pictures, and read backlog (stuff slack does). However the backend chat server should be the decentralized existing ones, efnet/freenode/etc.
So maybe its time to re-invent slack and make a pretty UI to access usual standard IRC. ie. a new slack that uses old irc networks (decentralized networks) as its backend. But also allows users to talk from mobile apps, browsers, etc