Supposedly they wrote possible futures for every single TNG regular (and recurring) characters. I simply can't imagine them *not* having a plan for Crusher. The fact that she's just MIA is narratively jarring. She's one of Picard's oldest friends and sounding boards. If she were dead, there would have been a mention of it. The only thing that makes sense is if they had a falling out of some sort. Or Beverly is in an unreachable place.