I guess it could be possible, but looking at the XMPP <-> GoogleTalk situation, it is very unlikely.

• Embrace the open standard
• Extend it with some propriety add-on, and because you have 1000 times users, you now become the "standard"
• Extinguish the open version of the standard because users expect that all the things should work together; and now the open versions are considered "less" because they cannot work with the propriety bits.