When such a star goes supernova a GRB is always 'a' possibility, so does the collision of a neutron star with a black hole. But the article also states that the chance of that GRB hitting us is pretty low, since it's polar axis is not entire aligned with Earth. Also, when it still takes 500,000 years before star A goes supernova then the system and also our solar system has moved away from our current location. The distance is roughly 7,500 light years, pretty enough room for an eventual GRB to simply miss Earth. I would not loose any sleep over it.