How would you solve the IM problem?

Artem Tashkinov writes: The XKCD comics has posted a wonderful and exceptionally relevant post in regard to the today's situation with various instant messaging solutions. E-mail has served us well in the past however it's not suitable for any real time communications involving video and audio. XMPP was a nice idea however it has largely failed except for a low number of geeks who stick to it. Nowadays some people install up to seven IMs to be able to keep up with various circles of people. How do you see this situation being resolved?

People desperately need a universal solution which is secure, decentralized, fault tolerant, not attached to your phone number, protects your privacy, supports video and audio chats and sending of files, works behind NATs and other firewalls and has the ability to send offline messages. I believe we need a modern version of SMTP.