11 weeks later and my X4 is still out of action.
Just like I had feared, parts are difficult to find and are being manufactured on a need-basis for new orders. Resale parts are literally inexistent. Parts are coming from overseas, Germany and elsewhere, and not from within the US.
Due to this, the body shop in unable to give me an ETA at all.
Moral of the story: Don't get into an accident in your X4.