As a final follow-up, I had not seen the worker in about a week, but saw her again last night. While I did not see her laying, she was still receiving a queen response from surrounding bees. The queen is laying very prolifically and has a frame and a half of brood. The middle frame of my three-frame observation hive is completely full of capped brood - I can only locate one possible drone cap in a worker cell and no actual drone cells apparent. The hive population is dwindling some (as expected), but my first bees should be emerging before too long and the queen is active, healthy, and pleasantly elongated. I suspect that don2 is correct that timing just happened to work out perfectly, and I also wonder if it has anything to do with the fact that I have only ever been able to locate a single laying worker. Perhaps the hive had not completely turned to a laying worker hive because the emergency cells were plenty far along.
Given my experience with this hive, I also suspect that a protected queen cell introduced into a laying worker hive as discussed by capt44 might be enough to eventually rectify the situation without even shaking out the hive. It would be interesting to conduct an experiment to explore this, or even hear from others that might have attempted this. Shaking a hive can be quite disruptive, especially since many of the newly emerged bees will never make it back. So if we were able to determine that it was unnecessary, that would probably prove to be quite useful.
And, to capt44, to your point about not being able to find the laying workers, I discussed this briefly in one of my earlier posts. Really, the only reason I was able to find and figure out what she was is because I initially saw the queen response from surrounding bees. While one could probably take a significant amount of time tearing through every last frame of the hive, and possibly find a few of the laying workers this way, I doubt you would find all of them. This is at least in part due to the fact that there were times when I watched my laying worker scrambling erratically around the hive too quickly for surrounding bees to give her a queen response. As an interesting side note to this paragraph, if I were given a small-ish group of bees and told that one or more are laying workers and asked to identify them, I might be able to. But this would probably take fairly close examination, and I don't know that I would correctly identify each bee in the group since she looked little different than an engorged bee. One of the things that I noticed was it appeared that the abdomen wasn't completely smooth and perhaps had a couple of bumps under the chitin on the anterior side - I described this as "distended" in my previous post. But again, I agree that finding these things in a full hive with bees everywhere, would be quite difficult as the differences are subtle.