andi Thanks for the notices, am not too active here but at least I know to update my bookmarks now. IRC should be kept, and it's good if it has been moved over to libera, and it's good to see that most of the projects I'm in have moved over. (Ofc the best alternative would be to self-host, but there's other considerations at that)
May as well mention that from a devel / programmer / advanced user perspective, switching to alternatives like Discord or Mattermost is rather cumbersome - Discord is proprietary, their desktop client spies on your machine, their web client is tremendously heavy for when what you want is to ask one question or two, and the people who would be using IRC as a means of contact or enquiry do it because of the advantages that IRC has over the alternatives (simple, free, no distractions right-to-the-point, easy to move the service if needed), not because of popularity. If "modernizing" the communication on that branch was a discussion to be had, the successor could be XMPP (but I think that's where the status of client software is an absolute ride, unless things have chanced since I last checked).
Then again, for technical discussions, the forum is a better workable platform, since you have a level of persistence of content (and better facilities to share code samples) that "xat" services don't have. An important feature of support forums is that the solutions (and the questions!) are available not only for the askers but for the community in general, and there's no way something like Discord or Slack can provide that.
For newcomers, or for people who don't even know Dokuwiki but arrive to ask questions somehow, sure, put up a Discord welcome chat, or even a Whatsapp or Telegram chat if so desired, bridged over to the IRC. But in the end the people who are going to coming in because new are going to find the solutions to their questions on the already existing wiki (eg.: "how to download?"), or in the forum, anyway.
desbest I don't know how up to date on the situation either you or I are, if at all, but the response to the situation at freenode is not at all FUD and in fact follows patterns clearly established in takeovers of community projects since at least 2005. The new owner bought Freenod a few years ago actually, but did it "under the hood" since the project did not have an established legal governance. His claim to ownership comes from de facto (he used to pay for the hosting services) rather than from de jure. Since the announcement, long-time Freenode mods and ops have been censored, the Freenode documentation has been made to advertize the new owner's other personal VCs, now projects with their IRC channels there have had their channels, as well as their auths, taken over by the new owner, and have even been prevented from communicating to their users that their channels are being moved over to libera (even being banned as a result). The purpose of the takeover is clearly to appropriate foreign communities (with what intent I don't know, there's not really much sellable info on a /nickserv dataset that would be not already freely available in eg.: haveibeenpwned).
The best-case scenario is that the new Freenode becomes the Quora to Libera's StackOverflow.