Last I heard, they were going to split trains at Jacksonville. The split trains will head to Miami via the FEC line. Now I didn't hear Palmetto specifically, but I think the Silvers are the obvious candidates for that.
The proposal in the 2011 PIP report was to split the Silver Star at Jacksonville with the split section running on the FEC to Miami. With FL funding the construction of the cross-over track for commuter service, the physical connection for Amtrak to run on the FEC will be in place in a few years. But any such split will depend on All Aboard Florida or FL extending a corridor service to JAX and the AAF & FEC arrangement allowing Amtrak to run an LD train over the FEC. If a split Silver service does eventually happen, it will be long after the Viewliner IIs are delivered. Even with all the delays in the Viewliner II production.