What's next for Instant Messaging?
First, let's examine what Instant Messaging, regardless of the provider, really is: Instant Messaging is a simplex (i.e., 2 people cannot "talk" at precisely the same time -- you may experience this on old speakerphones at your office) connection between 2 users with compatible software clients installed (doesn't matter if the software is installed on your phone, computer, PDA, etc., the software has to be compatible with the service provider).
Current enhancements to IM clients include video conferencing, which enables duplex (i.e., both people can talk at precisely the same time and they can both hear what the other is saying) audio (forget about the video component for the moment). Now, the Apple iChat client actually has a connection mode that does forget about the video component, called "voice connection." Imagine if all your friends used iChat compatible software (iChat software, by the way, is available for free from Apple for Apple users and is compatible with free AOL Instant Messenger software for Windows).
Do you know a lot of people that use AIM on their Windows machine? I sure do. Voice Over IP? Why not Voice Over IM? Imagine if AOL Instant Messenger was able to route calls to people in your Buddy List via IM and route calls to people you don't know via IP. Then add the video component back in. Suddenly you have a very powerful product. And the best way to get people to use it (and maybe pay a monthly service charge for IP calling)? Give it away for free (if you give it away for free and keep adding features, you work your way towards becoming the defacto standard).