Once it's gone it'll be gone forever.
Pretty soon the Chevrolet SS will go the way of its Australian platform mate, the Holden Commodore. That's because the Commodore itself will cease production in 2017. In case you didn't know, the SS is built alongside it in Australia. This effectively means that in just few years' time, Chevrolet will no longer have a rear-wheel-drive, V8-powered sedan in its US lineup (and Australia's Holden division will be finished entirely). As it stands now, GM doesn't have a replacement RWD sedan lined up for either market.
Now, that doesn't mean it won't happen at some point. It's just unlikely. Why? Because the SS is a niche model, catered specifically to those seeking RWD performance and handling. It's not a mainstream sedan, and Chevrolet is importing only as many as there are orders for. And generally speaking, FWD sedans like the Impala and Malibu have greater appeal. Now, it's possible that a new SS could one day happen, possibly to be built on the same platform that underpins the Cadillac ATS and upcoming next-gen Camaro. But for now GM isn't saying anything. So if you want a new SS, now's the time.