Would the world end in fire or ice? Dean didn't know. The apocalypse may have come and gone, but the world didn't end, so it still could go either way. If he had his choice, though, he'd go with fire.
Hell was many things and Dean knew most of them from personal experience. But fire wasn't one of them, not at least as flames and light and heat. No. Hell was pain and burning, there was crap that stuck on you like napalm and ate through you little by little until there was nothing left. And it was hot. All of hell was filled with a burning, suffocating heat that pressed down on everything, oppressive and inescapable. Everything burned when you touched it or when it skewered though you.
But it wasn't fire. Oh, no. Fire was liberation. Fire was life. Fire was freedom. He should have known that. Fire destroyed evil. Fire saved you. It even kept you safe after you'd died. Fire consumed everything it touched, burned it into ash and left nothing to twist and torture and mold into evil.
Would the world end in fire or ice? Dean sincerely hoped for fire.