His problem is spot-on, his solution is just a little...whack. GMs brand alignment should look a little more like this, IMO.
Chevrolet -- Mainstream volume, covering most models and trim levels. Look much like it does today, only more competitive.
Saturn -- Upper-trim volume, targetting customers looking at V6 Camcords or Altimas, Muranos, etc. Picks up where Chevrolet left off.
Combined Chevrolet and Saturn should have the biggest chunk of GMs marketshare. Both brands together will cover Hyundai, Toyota, Honda, Mazda, and Nissan.
Pontiac -- Niche sports/performance oriented premium cars. Division whole would sell no more than 100-150k a year. No FWD. AWD or RWD-only. No large cars, nothing larger than mid-size. Small Zeta would be acceptable, full-size Zeta would cause too much overlap with Impala (Zeta) SS. Acura is main target.
Buick -- Premium/Entry-lux mid-size and full-size cars and SUVs. FWD/AWD EpII Lacrosse, RWD/AWD full-sized Zeta Lucerne, Enclave, Zeta-coupe and convertible. Lexus competitor.
GMC -- Premium/Entry-lux mid-size and full-size SUVs/trucks. Looks much like it does today.
Pontiac-Buick-GMC, one dealer network. Combining all brands into one dealer creates a full lineup of vehicles that starts where Chevrolet and Saturn leave off in price and offerings.
Cadillac -- Mercedes/BMW/Audi.
Hummer, Saab -- Quirky cult brands. Expendable in America, GM could easily lose both and make up their sales in other brands.
Thats my thoughts on what GM should look like. Each brand offers unique vehicles with very very little overlap occuring between optioned-out and base-level vehicles. (EG, optioned-out Impala vs base-trim Lucerne).