IF GM wants to battle Ford and Dodge then I think a strong case can be made for both a ZL1 and Z/28.
But what is their strategy? Go toe-to-toe with the Hellcat and GT500? Then if that, we will see another ZL1 - possibly. If not, I imagine the ZL1 will not reappear.
Since the Z/28 focus is more aimed at the previous Boss 302 and the GT350, it makes sense it will remain but who knows? There is a place for both in the Camaro enthusiats' world.
But - while there is a place for both types of performance, that doesn't mean that one platform could not be spec'd out to do either from an order sheet.