Here are reasons I think email is dead:
- Email is slow -- other technologies provide instant access and response.
- Email is unreliable -- your messages might not make it through to the recipient. I regularly get and receive calls to make sure an important email has arrived.
- Spam -- like college tuition and the price of oil, spam increases, despite new so-called solutions to fight spam. I don't think we'll ever win the war on spam. But other communications tools, like instant message and contact via social networks, can reduce --- but not eliminate -- the quantity of spam. (Case in point: TwitterSpam: people who select thousands of people to "follow" on Twitter in the hopes that people will "follow" them in return in the hopes they'll check out whatever it is the TwitSpammers are trying to sell.
- Email tends to overwhelm "in boxes" with information users didn't need. A much better way is to subscribe to RSS feeds, resulting in less clutter, less guilt.
- Email, for most of us, is less likely to have significant impact beyond our immediate friends and family. And every time someone forwards the email, the meat of the email gets pushed lower and lower on the screen, formatting changes, etc., diluting the impact it could have.