Superman will put on a very good show, but in the end, even he will not be able to get past Kuurth's strength, durability, and untiring nature. Cain was a fully stack-able character as Kuurth. Alone, Cain was enchanted by Cyttorak as we all know, he was a very heavy hitter due to his impossible durabilitty. There is no way that Superman can stand there and bang out with him, if he did, he would lose. The beating would eventually be worse than his DOS beating (yes I know it was a tie). Unlike Doomsday, Kuurth would not be hurt in the least by Superman's most powerful blows. He'd end up depleting his reserves and lose.