Domestic and import full-size truck and SUV sales are declining with fuel economy concerns, so manufacturing two of the same brand is not a profitable long-term business model. Chevrolet and GMC trucks and SUVs are essentially the same vehicles. Chevrolet models cost less, have equal or better quality and fuel economy, and outsell GMC models more than three to one. Toyota and other imports don't manufacture two of the same full-size vehicles under different brand names; it does not make sense, economically, for GM to continue producing both GMC and Chevrolet.
Advocates who hope to keep GMC as the auto industry changes to more fuel-efficient models want to continue a business strategy that will ultimately be as unprofitable as the now defunct brands of Hummer, Pontiac, Oldsmobile, Saturn, and Saab.
Follow the import business model, eliminate GMC now, and save the costs associated with the extra GMC manufacturing processes and distribution channels, which will not be part of a long-term solution. The new GM will be more profitable going forward without GMC if Chevrolet produces and sells all of GM's full-size trucks and SUVs.
GM won't need government and taxpayer support again if GMC is eliminated now.