The GS, Impala and GP all shared similar platform. Not too much of a stretch to envision that IF the GP were still being produced today that it could bear some resemblance to the cars it shared a platform with in the past.
Regardless, the one or two reviews I've read on the GS appear positive. I'm not a new car buyer or a leaser but it will be interesting to see how the latest GS is received and how it holds up over the next few years. Could be worth purchasing a gently used one in a few years if my 04 GP ever goes to that big junkyard in the sky (which I hope it doesn't for some time!).