Of course, Scott actually got mad at me when I said that was silly because no one would think she was really dead, but there is no reason to think she died. It kind of fails as a cliffhanger in my book, because we all know they won't do Castle without her. Too much of what the show is is wrapped up in their relationship.
Now, will she remember Castle's declaration after her recovery, or will she pretend she doesn't remember...that's a different story.