I personally think the only player that kills hopes of a SB win is an elite QB. If you lose that, you may well lose any chance at winning the SB. Although Clady is an amazing player, it's not like he is going to be replaced with a potato. He gets plays off so quickly that he may only see one or two times a game where he has to throw it away prematurely. I don't think it's a dream-killer by any stretch of the imagination.
If we lose a few more franchise players due to injury, then ok, the cumulative effect may hurt us. But we'll actually be getting players back, and probably will be better off come the playoffs as long as we stay healthy.