Over time I think these kids will learn that in the real world where you're trying to get work done, IM is annoying as hell. It's like having someone call you on the phone every few seconds. No thanks.
E-mail, web forums, and other "delayed" forms of communication are so much better for almost everything.
IM is really only a substitute for the phone. And then only when it makes sense, like to save money on long distance or when you need to be quiet.
People ask why I'm never signed in to MSN Messenger, or Skype, or whatever. Here's a sort of explanation from a reader of Slashdot (comment 19948169). This comment is in reply to a Slashdot post about a News.com story about kids saying email is "dead."