When the US builds a new aircraft, it goes into LRP (Low Rate Production) initially. I wonder if it can do the same at the tail end, with the line still open, but say half the rate of production? Stretch out the already-ordered forgings a bit longer..
Still, Mr Boeing wouldn't like that, because it allows potential clients to put off the purchase decision. We do this kind of thing at work frequently. Lifecycle management of once-desirable products is a very difficult thing to get right without upsetting a lot of folk.
Boeing will close the Long Beach plant when the last C17 is produced, so perhaps they'll make more money (or save more money) from that action than any number of residual C17s.