I think it's a very naive outlook. It shows a lack of understanding of the phone as well as e-mail. I don't think one will replace the other. TV never replaced radio. They're different means.
Phone is synchronous.
You want to talk to someone when you're ready and they have to be there. E-mail is asynchronous. They don't have to be there. The other thing is e- mail requires a lot more skill to answer. You have to be able to read, you have to be able to write, and you have to be able to grammar check and spell check.