2) If chess is a win for black, premises 1 and 2 are satisfied but not the conclusion.
Then the whole game of chess would turn out to be a zwichzwang!
I agree this is extremely unlikely to happen. But surprisingly enough, nobody has been able to prove such a result. In a lot of games, it can be proven that the second player cannot win (so the game is either a draw or a first player win), since the first player could "steal" the second player's winning strategy if he had one. In chess, such a result cannot be easily obtained.
2) If chess is a win for black, premises 1 and 2 are satisfied but not the conclusion.
Then the whole game of chess would turn out to be a zugzwang.