I see that the Lords of WordPress have decided that I don’t need to see previews of my posts any more, unless I use their “visual” editor, which I dislike. I also don’t see a way to schedule posts for future publication, despite the claims in the “Help” tab in the editor. I’ve been using WordPress for about ten years now, but if there are many further “improvements,” I may look for another platform.
Update: the editing page is back to normal.