Despite your decision that keeping Pontiac around is not a good business plan, I am asking you to consider saving some of Pontiac's product. Over the last few years, you started to build some Pontiacs that were actually exciting.
(Photos courtesy of Edmunds)
You should try to save the G8. This car is the best large sedan GM has sold in the U.S., outside of the Cadillacs, in a long time. Yes, it is expensive, and is being shipped from Australia. I think it would make an excellent top of the line Chevrolet--like an Impala with soul. It might make an interesting cop car, too, if you could work out the economics. Once people realized it was here to stay, sales would improve.
You should save the Solstice/Sky platform. This is a fun little car, and though it needs some qualty improvements and some refinement, it is one of the few cars you build that people actually fall in love with. I met a guy that got one from his wife as a 50th birthday present, and he acts like it is his mistress. Restyle this as a Buick, or perhaps as another Chevrolet, a "baby Corvette". The Solstice might also be an interesting platform for an all-electric sports car, something to compete with Tesla.
Finally, you should to do something with the Vibe. Not because it is that exciting of a product, but because it is a solid product with good quality numbers. Since Ford killed the 5-door Focus, this is one of the few domestic tall compact hatchbacks. It is much better than the Dodge Caliber. I'm not sure if the Vibe would make a good Chevrolet, as far as styling goes, but I do think it might make a decent Saturn. Maybe build the Vibe as a Saturn for Roger Penske, if you don't see it as a Chevrolet.
As for the G3, G5, G6, and Torrent, no tears shed here.