Right now, this really doesn't make a big difference. All of the rest of the rotation players are healthy. Williams (and Scal when he is ready) are both solid enough to step in to pick up a few minutes, and help out if there is foul trouble.
If this injury was in February, when everyone else is starting to get worn down, then it could be a problem, but right now, it shouldn't be a huge deal.
What will be the real question is how Baby deals with it. Does he sit on his ass, gain 15 pounds, and have to start from scratch when he returns, or does he take this opportunity to hit the treadmill hard, lose another 10-15 pounds, and come back with a purpose? I honestly don't know what to expect.