I didn't know they moved but I know Rolling Rock isn't the same beer it was in the 70s.
There are rumors that the plant may reopen as the former owners have been in talks with Anheuser-Busch to reacquire the brand. These talks have been ongoing since 2009 and, I suspect Anheuser-Busch will hold off on a final sale until the brand has been sufficiently devalued to ensure it will never compete nationally again.