I have literally never fantasized about this. The thought never crossed my mind. I think it's because it's too terrifying, too total, too real, and too 'unnatural' for me to fantasize about. I'm already so afraid of death from above, I don't want or need to put more thought to it. Sometimes I do imagine post-apocalyptic scenarios without humans; or an Earth where the land is scorched by cataclysmic and global natural disaster. Life must begin again. It's fun to imagine a new era of Earth; how it would evolve. But nukes? Can't say I've ever approached it from that angle.