I suspect the Z/28 will last until the end of the 5th Gen, then take a short hiatus as they ramp up the 6th gen.
Note, if I've gotten any facts wrong in the above, just ignore any points I made with them
don't believe a thing you read about the next gen Camaro -- as history has proven time and time again:
WE DO NOT TALK ABOUT FUTURE PRODUCT PLANS PERIOD FbodFather
Camaro5 Fest sub-forum