[wanda]

Ubuntu and its derivatives have hardly killed off less user-friendly distributions like Gentoo, Slackware, Arch or even Debian. On a broader scale, Chromebooks may be gaining popularity but they will not be replacing the ultrabook or even the netbook so easily. No single method of messaging has ever come close to replacing email. No matter how FOSS it becomes, Windows is not going to displace Linux or BSD distros when it comes to servers. Bitnami is not going to stop people rolling their own web applications and solution stacks.

Slack has its use-cases. Collaborative chat for non-tech people who either do not want customisation, or cannot be trusted with it, to communicate rapidly from any device and easily integrate with popular filesharing/social media applications in private channels. Sounds great but it's bloody specific when you think about it.

In a way, if you were to slap Microsoft Office apps into it, Slack would be what Office365 should have been. And it may yet prove to be an Office365 killer. but it is not going to displace IRC. As another comment has said, IRC filters users by their ability to actually learn about it, rather like cryptocurrencies--they're not very complicated at entry level but there is an entry hurdle that precludes any old numpty from joining in. IRC has long been a haven for people who want to avoid at least a percentage of the web's numpties.

Slack won't even replace forums because fundamentally a Slack team has no identity, no creative control. I can't see SomethingAwful or Hacker News being replaced by Slack. It's not even just about style/design: HN's arc implementation, and basically any community's solution stack, is part of what makes it a separate entity. Slack is too impersonal, too clinical to make for much of a walled garden as many forums seem to be.