I don't doubt it. I think we will miss it in the passing game, but not so much in the running game. But, I think that Lance Moore will take a lot of Bush's snaps and run a lot of similar routes. Moore does not have Bush's speed obviously, but he does have better hands, or at least better concentration, and his quickness is similar.
I also think that Ingram will surprise us with his ability to catch the ball out of the backfield. We do lose the threat of Bush's big plays, but he had them so seldom and when they did come they generally came in bunches, that I doubt it will hurt us overall. I also think it will force Payton to be more diverse in his third down play calling instead of counting on Bush to squeeze out three yards. I think the offense will be different, but not necessarily better or worse without Bush.