What are the limits on baking at 400F/200C? I recently saw this video and the accompanying article on the New York Times website, which describes cooking a Thanksgiving dinner (including turkey, a crumble, dressing, and a sweet potato gratin) in a 400 degree oven, plus some things on the stove. It made me wonder whether you could apply the same principle to, say, cooking for the whole week on a Sunday morning: set the oven to one temp and just move pans in and out as needed.

So here's the question: what are the limits of what you can do at 400F/200C? I know I can roast meats and veg at that heat. Can you do breads? desserts? casseroles? When is that heat too high to be practical?
That temp will cook many, many things with no problems. You would simply have to adjust cooking time.  Also, regarding your article and video, many Thanksgiving items are simply casseroles that need to be heated through (other than the turkey), so one temperature makes sense.  Speaking more broadly, oven temperatures are wildly inaccurate.  So, a setting of 400F is often meaningless, unless you are carefully monitoring your temperature with an oven thermometer placed inside. It would be fairly common for your oven temperature to be significantly (as much as 50 F or more) different from your oven setting. If you have the time and energy, an oven set at 400F could cook things that need a much lower temperature, provided you shuffle your items in and out of the oven with the correct timing. Perhaps not so convenient, if you needed to set a custard in a water bath at a low temperature.  You may also be limited in cooking that requires very high heat.  For example, while you could bake an edible Neapolitan pizza, on a stone, in a 400F oven, you would simply get a better result in an 550 degree oven (and in less time).  So, practically speaking, I think the bottom line is that, with the exception of some specialty items, the limits here are mostly time and convenience, rather than temperature.  You could eat well using an oven that only had a 400F setting. I would say 475 - 500F would be less practical, but then again, if you only had one setting, you would adjust your cooking to the heat source.