Eventually, yes. GM has an obligation to support their cars for a certain period of time after their production and sale. In the past, I've read eight years and more recently I've read ten years. So parts support for a 2013-2017 model should be available until later in time than for a 2008-2009 model car.
For things that are still in use or produced in large numbers, like the SL80 automatic transmission, industry support will be around for a long time. Body parts for a limited production vehicle, not so much. When GM no longer has a desired part, the salvage yards and Car-Part.com become one's friend.
According to Wikipedia, 28,159 G8's and 12,860 SS's were sold in the US. So there might be more G8's in the salvage yards. Also, a lot of G8 mechanical parts were shared with comparable year Camaro's.
I believe the total G8 production was around 48,000 total between sedans, GTs, and GXPs. More made than SS’S.
Don’t know if those numbers include Canadian cars.