Realistically I don't see how it would ever not be managed by a corporation. Your average person doesn't know how and doesn't want to manage their own messaging system. They are just going to offload that responsibility to a corporation to do it for them. We are just going to have exactly the same system we have now. Just called some else besides email.
I wish there was a better solution but I am not seeing a way that doesn't just end up the same as email.