I've been following a huge thread about this on another board and the consensus is that there will be three separate lines: Pop/AoA to CBR, CBR to DHS and CBR to Epcot. Riviera is expected to be a mid-way station on the CBR-Epcot line, but details are not public at this point. Going from Pop/AoA to DHS or Epcot will mean going to CBR first and then transferring to your desired park line. CBR will be the hub, but it's not clear how the queues etc. will work. The system is expected to have a huge, possibly unprecedented, hourly capacity. Numbers of 4 to 5000 people per hour per individual line and direction have been thrown around, which is the equivalent of 80 to a 100 buses per hour per direction if you assume 50 people per bus. There may be wait times at peak moments (at park closure), but overall this should become a fantastic system with short wait times, short rides, and best of all: a continuously moving queue. Oh, and the gondalas will be in the secure zone, so no more going through security at DHS or IG. Pop's about to get popular!