i agree that it will be interesting to see what happens to draco. he failed his master and although others have been tortured for failing him before, being able to kill the leader of the opposition army when he is unarmed and defenceless would have to be a fundamental requirement for being a death eater. even the good guys can kill (aurors were given authority to kill death eaters in the first war by crouch snr), so draco's inability to kill DD would sure result in LV killing him.
whether he will try redeem himself - i'm not sure. he went with snape and the other death eaters, presumably to LV to give him the good news, so unless there is another plan LV wants put into action that only draco can do i would say he was dead already.