IFF the refs "let them play" (and that means both sides) in game #7, this isn't the end of the world. At this point, Bynum is basically a figurehead to give the Lakers the illusion of a physical presence for ten min. or whatever he ends up playing. Perk has a similar role-- he's absolutely necessary to guard a healthy Bynum but since that isn't the case, his role is more to establish a physical presence and take pansy ass Gasol out of the game.
Now the good news is that Sheed can do the exact same thing, while providing much better offense. He's not capable of playing big minutes in general, but for one critical game, he can certainly log 30 min. The reason the aforementioned reffing is important is that Sheed is instantly in foul trouble in every game, largely due to ticky-tack contact (which is unfair given how they are reffing things in the last three). I actually like seeing Sheed out there for a big game because he's a proven playoff performer and he pulls either Gasol or Odom away from the basket on defense, which really helps out the Celtics rebounding effort (and at least mitigates the loss of Perkins).
So my prediction is that if Sheed can give the Celtics 30min, they will win on Thursday, whether Perkins plays 0 minutes or 10 figurehead minutes.