At one point, he quite audaciously predicted that the Soviet Union was headed for collapse. If he'd lived longer, he would have seen that his prediction should have been even crazier: not only did the Soviet Union fall apart, but it did so without starting a major war, or nuking any cities.

And don't even get me started on his books where we've got interstellar travel, guided by computers that are the size of a room but barely faster than someone with a slide rule.