There's no reason to get rid of it because Pontiac is being shut down. Parts will still be available and any service/warranty work can be done at ANY GM dealership.
There's no need to rush into a decision like that because of Pontiac's situation. You're fine, there's nothing to worry about. The only thing that might suck is if you're in a remote area and your local Pontiac dealer is closing and there's no other GM dealership in the area.
Other than that there's no reason to get rid of it unless you're just looking to get into a newer car.