A magnetic shift will do nothing to humans. It has happenend hundreds of times in the past, and will happen hundreds of times in the future. All it is is the Earth's outer core (mostly iron and nickle) steadily reshifting it's current. The outer core is responsible for our magneti field, and when this 'disaster' does occur it will be roughly one day, where you may get a severe sunburn if you stay out too long. I'm not sure about the damage done to satellites, but it would be severe, as the magnetic field of the Earth is the main shield for our satellites. We'd have communications down across the world, most radio stations would have a lot of interference. After the field re-aligns all we will need to do is switch our compasses around and repair our satellite fleets.