I'm back in the camp that believes we'll see the Z/28 in the Gen5. It's already been said the C7 Corvette will arrive first in base form, then Gran Sport, Z06, etc.....
So I think the Gen5 Camaro is leading up to the end of it's life cycle with a Z/28. We just need to wait for this darn Corvette to be announced with the next generation of engines. We got 2 model years left, so we should be seeing the Z/28 next Summer.