It's called a Ford Expedition. Or a Chevy Tahoe/Suburban.
This GMC prototype is getting an unfair rap here on FR, like most innovative, smaller vehicles. So, it doesn't tow a boat, or hold a sheet of plywood. Plenty of useful vehicles don't, and there is a market for them.
On the plus side, this concept will offer the packaging advantages of the Scion xB, which was an obvious influence. Those advantages are an amazing amount of room for the exterior size, and the exreme flexibility in configuring that interior space. This GM effort is better looking though, more aggressive, very wheel-oriented for more visual excitement and is overall a more aesthetically appealing vehicle than either the xB or the Soul. With a 1.4 liter four cylinder, fuel efficiency should be well into the mid-30's as far as highway mileage. That's a lot of function with a low operating cost, which has it's appeal even with controversial styling.
On the down side, GMC styling cues are probably what is making this boxy little minivan/station wagon more beefy and appealing. But, such a vehicle is highly questionable in the GMC "Professional Grade" market positioning. The larger Terrain is even questionable. They're running the risk of muddying the waters, as far as the meaning of GMC. That's what killed Saturn, Pontiac and Oldsmobile. The brand ceased to mean much of anything. GMC does. They should leave it alone, and stick with trucks, SUVs, offroad vehicles and work vehicles. This thing should be badged a Chevrolet. But, it won't, because it'll cannibalize the HHR.
Should GMC decide to offer a diesel option, get an all-wheel drive option in it, work on the content as far as techical "gear" and functional add-ons, maybe it can be made to reside comfortably in the GMC lineup. If they know what's good for them, this is what they'll do.
Back when my 1980 Chevy Pickup was on it’s last miles I said the same thing about having an old station wagon like my dad’s. Enough room to carry my family of five, but also be able to carry plywood (and everything else). But I didnn’t want a king cab with a eight-foot bed for suburbia. And I also wanted the option of an open bed to dump dirt in.
Then I saw a review for the Chevy Avalanche! Although I guess the Suburban or Expedition is closer to a station wagon - the Avalanche was exactly what I had been looking for. Eight years later I have no regrets. I hope Obama gets out of the car business by the time I need another truck.