It’s interesting to me that while GM and Ford are dropping various lines including Pontiac, Oldsmobile, Saturn, and now Mercury, Toyota added the high level Lexus and the low end Scion. Honda added Acura and Nissan added Infiniti.
Adding and dropping lines is nothing new. GM dropped the Oakland and only its entry level car, the Pontiac survived. Around the same time, Buick introduced a cheaper line called the Marquette and Oldsmobile followed suit with its Viking. These cars disappeared quickly. Sometime in the 1930s, Cadillac introduced a junior model called the LaSalle, but it lasted only through 1940. Chrysler had a make called the DeSoto that was introduced in 1929 but disappeared with the 1961 model.
I think that what made the Pontiac and Oldsmobiles survive was that through the 1940s, 1950s, 1960s, and into the 1970s, the GM brands were all different. The engines were completely different. The Chevrolet, Pontiac, Oldsmobile, Buick and Cadillac V-8 engines were completely different. In the early 1950s, Chevrolet had an overhead valve 6, Pontiac had a flathead 6 and a flathead straight 8, Oldsmobile had an overhead valve V-8, Buick had an overhead valve straight 8 and Cadillac had its own overhead valve V-8. Each division developed its own overhead valve V-8 engine. I think the problems started when the GM cars all became the same except for the badge. GM should have followed the example of Proctor and Gamble. Tide and Cheer are completely different–not the same soap in different boxes.