I think they have a lot covered. From the base, to the Z51 package, to the base Z06 on up to the Z07... however...
there will be a market for a Grand Sport version with the widebody kit including a couple of items from the Z06. Whether they release it or not time will tell.
You have to figure that a ZR1 version is at least been designed/conceptualized and is waiting in the wings. It may never see the light of day. Remember, the C8 should be here sooner than then C6 --> C7 timeframe so that could squeeze out some low sales models.