First of all, it is 99% sure that Pontiac will be discontinued. The value of your car will not be impacted that much, in fact there may be a little bit of a bump in value as people try to get the last of the brand.
Parts will still be available. Many of the parts in a Pontiac are the same as in a Chevrolet, and there are going to be aftermarket parts available for years. You can still find parts for Oldsmobile, and that brand has been gone since after the 2004 model year.
As to those who say that Pontiac is part of Chrysler, "Here's your sign!!"
Chrysler = Chrysler Dodge and Jeep (Plymouth discontinued)
GM = Cadillac, Buick, Pontiac. GMC trucks, Chevrolet, Hummer, Saturn, and Saab (Oldsmobile Discontinued)