LWB Zeta has been going to LGR ever since the UAW spilled the beans about what US plants got what. Hamtramack gets the Volt, and a few other cars.
Regarding ChevyRules comments you completely glazed over the fact that the Zeta SUT's are RWD. So for that market there are 3 choices on the table: RWD GMT-700 BOF, RWD Zeta Unibody, FWD Lambda Unibody.
As of right now GM is looking at the following (US Market):
(name) Denotes up in the air.
Micro:
(Beat)
Gamma II:
Saturn Corsa, Chevy Aveo
Delta II:
Chevy Cobalt, Chevy HHR, Saturn Astra, (Buick Skylark)
Epsilon II:
Saab 9-3, Saab 9-5 (LWB), Chevy Malibu, Chevy Impala (LWB), Buick LaCrosse, Saturn Aura, (Pontiac G6)
Alpha:
BLS Replacement, (Pontiac G6)
Zeta:
Camaro, G8, (Low Volume RWD Chevy), (GMC Crewman), (Chevy Crewman), Lucerne Replacement (LWB), DTS/STS Replacement (LWB)
Sigma II:
CTS
Theta:
Equinox, Terrain, Vue
Theta-Epsilon (Theta Premium):
Buick CUV, BRX/Provoq, 9-4X
Lambda:
Traverse, Outlook, Acadia, Enclave, (Traverse SUT), (Acadia SUT)
Y-body:
Corvette, (XLR)
GMT-900:
As is today
GMT-700:
H3, H3 SUT, HX/H4, (Colorado), (Canyon)
GMT-360:
Dead
Kappa:
Solstice, Sky
N-Body:
Vibe
The Pontiac Wave and G5 may be retained for Canada, Mexico. Buick Skylark replaces G5 in US channel, and Buick LaCrosse replaces G6 in US channel. Since the G6 MAY not go Alpha, the backup plan is to reskin a Malibu for Pontiac to replace the G6 along with the LaCrosse in the US channel. That along with the aforementioned Zeta, Lambda, GMT-700 debacle are the most fluid in GM's line-up.