If IRC is losing users (and that's a pretty massive if), it's most likely due to advances in other technologies such as many different IM protocols which are simpler for the average non-tech person to speak to a few friends, VOIP, SMS texting, and now video messaging over mobile phones. All this stuff just means that for someone who wants to talk to people who they already know, IRC is not such a suitable option, and quite frankly, they're not wrong. IRC is still the protocol of choice for those who want to chat to new people, it's just that now newer, better methods exist for those who want to communicate with someone specific. Rather than a decline of IRC, I'd consider it as more of a focussing of IRC to the task to which it's best suited.
