Once the OpenWire protocol if fully implemented and documented
When will that be? Since Apache is a volunteer organization, it's hard to say when it will be completed. I can just tell you what the current state its. I would classify the current state of the OpenWire Protocol as being alpha/beta quality. It does not net support XA transactions and not all use cases are fully unit tested. Since the initial focus will be to to just make it feature and backward compatible, we probably will not be focusing on optimizing the OpenWire performance until thats done.
ActiveMQ development will NOT stop. It has a large user based and we will continue to incrementally improve that code base. Apollo is jus providing a fresh new platform to do some things better.