Unfortunately the chat messenger market is highly centralized. The most popular chat apps are closed-source so only the developer´s app is compatible. And since the number of users is the most critical factor, there is a huge inertia effect that makes very difficult for the new apps to grow. If the same happened to email, we will still have 50MB mailboxes.
There are great open-source instant message services such as XMPP and IRC but they were not able to grow enough when MSN started to fall. I hope in the next chat revolution an open-source protocol will get the biggest marketshare.