Seems like the best approach would be to create a discord<->irc bridge bot so conversations on either show up on both places. That way you avoid splitting the audience between both platforms (or you end up with even less people to talk to).
We had a Discord<>IRC Bridge (The remains of that are still on the Discord server in #donationcoder-on-irc) but it seemed completely pointless paying for it to stay online (VPS) on the basis that the only person who ever talks on the DC IRC recently, is the forum bot, lol.
Considering we have a fairly large community of people, it surprises me that not that many want to come and chat in real-time about various topics
Honestly, I'd prefer Discord to be the option over IRC (more modern features, always connected, etc etc), but in all honesty...if everybody chose IRC for DC...I would be happy anyway...I'd just like to see more interaction between members of the community XD