True - that's more or less what the UK car industry did during it's death throws. You could buy the same car with different logos on it - people even argued about which one was better. In fact they were prettywell all dreadful - and now all gone.

You can't put a Buick logo on a premium car like a Cadillac. First, a Cadillac costs more to make than people are willing to spend on a Buick. Second, doing that would reduce the demand for Cadillacs (since nobody wants something that is the "same as a Buick").

For non-premimum brands, GM and other manufacturers already do sell the same car with different names--even across coompanies. Most obviously, the Eagle Talon is/was the same as the Mitsubishi Eclipse except for the spoiler, and the Chevy Camero and the Pontiac Firebird were the same car with different body trim for a long time. Similarly, the Ford Taurus and the Mercury Sable are the same car except for some body styling. Toyota Corolla is the same as the Geo Prism, the Toyota Matrix is the same as the Pontiac Vibe, Ford Focus is sold under three different brands.

Doing this keeps the prices of the good brands high while selling cars for a discount when necessary. If you bargain the price of a Ford Taurus down far enough, the dealer will tell you that you can't have the Taurus for that price, but you can have the equivalent Sable.

He wasn't arguing that you could turn a Buick (cheap car) into a Cadillac (expensive car). He was arguing that if they can't entirely dispose of a brand, they could turn a Buick (car labeled a Buick) into a Cadillac (car labeled a Cadillac) with a simple label change.

A Cadillac is a car that has been labeled a Cadillac by the legal owner of the Cadillac trademark. Maybe "a car" is extraneous, too, though I suspect dealership contracts would have something to say about being turned into a Cadillac Pencil dealership. But still, I would imagine GM has a lot of discretion about what gets called a "Cadillac". (Maybe not, but that would be awfully far-sighted of the dealers to get a clause defining what a Cadillac is in their contracts and I would salute them for their legal prowess if they do have such clauses.)

Also, I have now typed "Cadillac" so many times it is no longer a word to me.

As mentioned in the article, the dealers survive off of maintaining cars that have already sold, not off of sales, so as long as there's enough cars to fill up their service bays, they won't just go out of business.