I think the introduction of the Z/28 for the 2014 model year makes things interesting for the 2016 Gen6. The Z/28 will definitely be back, but I don't see the ZL1 being available, at least not in the early years of Gen6.
Logic would say the SS would get the 427 and the Z/28 would get the LT1. The Z/28 would no longer be a stripped down car, have track goodies and be a good drivable week-end car. Also, I don't see the 1LE option clouding up the line-up.