Just another data point. My NRT-HNL a few weeks ago stayed on the 3-class config the entire time. I had no trouble switching to the old F cabin at T-24h with no status, and was surprised to see over half the cabin remain available until the last 2-3 hours before departure. I even saw one non-rev cleared into one of those seats pretty well ahead of departure, instead of moving a revenue passenger. I'm guessing the other pax were moved from business -- heard two of them (w/ 1K status) seem surprised to be moved.
Nice seat and glad I could try it out once.