Penguins: could they survive in the Northern Hemisphere?

It is a good question. Clearly there would have been numerous opportunities to move into the habitat of the Arctic but something is preventing it. It isn't a matter of the Penguin's instincts IMO. Storms and other occurrences happen that cause animals to move off course. They are common at the equator off the Galapagos Islands. Nothing would prevent northward migration. I would suggest that it is probably due to other successful animals already exploiting that niche. They wouldn't survive well on land with Polar Bears and Arctic foxes so that may be the deciding factor. Some flight may be a necessity in the Arctic whereas it isn't in the Antarctic. Perhaps because flight is not needed in the Antarctic to escape bears and foxes, penguins have been able to adapt their swimming ability more and are thus able to out-compete the flying competition that that they would experience from Arctic migraters.