There was an early integration of Tuscany in ServiceMix but it became completely out of sync with Tuscany as it was developed further, so it was removed from ServiceMix. At this time there are no official plans to integrate Tuscany by either the Apache ServiceMix team or the IONA FUSE team. But that doesn't mean it won't happen as ServiceMix is open source and anyone can contribute to it.
If you're interested in pursuing this work, you'll need to create a JBI service engine that wraps Tuscany. This will allow Tuscany to perform its work inside of ServiceMix. Then any JBI binding component can route messages to/from it via the NMR.