The discontinuation of the Pontiac brand has presented owners and mechanics with some unique challenges. The brand was eliminated because of redundancy; Pontiac sales were always healthy with respect to other GM brands. Nevertheless, they are gone for good.
The effect on the parts market is complex. The majority of the cars sold by Pontiac were mechanically identical, except for minor differences, to cars from other GM divisions. The Bonneville and the LeSabre were more or less the same car, as were the LSS, 88, and 98 from defunct Oldsmobile. For these Pontiac models, the situation is analogous to that of Oldsmobile. GM dealers and aftermarket parts manufacturers continue to list the Pontiac models in their parts guides. They continue to stock and supply parts for these cars, and others that are mechanically identical to Buick, Chevrolet, and Cadillac. The problems come from models that were unique to Pontiac.
The first issue to consider is the Pontiac V8 engine. Unique to the division, it was gone by the middle eighties. They were made in large numbers, though, and are all more or less the same in structure. Pontiac engines enjoy robust support from aftermarket manufacturers, and should not be a problem. Cars that are going to be hard to find parts for are: the Fiero, the Solstice, the Holden-manufactured GTO, the G8, and the Vibe. The Fiero is a non-issue today, and they share a number of parts with the Chevette and the Citation. The G8 and GTO are Holden-sourced cars which use American Chevrolet engines. There will be problems, but the increasing simplicity of shipping between the U.S. and Australia should ease them somewhat. The Vibe is mechanically identical to the Toyota Matrix, so parts will be available as long as Toyota dealers are willing to help. The Solstice is the biggest problem. It is a strictly GM brand that only shares parts with the Saturn Ion, and Saturn appears to be gone for good. So, the Solstice will be the hardest to find parts for as the years go by.