...you need to remember the production strategy Boeing uses that basically eliminates any cost difference in mutli-model production lines.. remember also that every customer is a variation. if the logistics would support throwing a -10 into the line, it would have little effect on production.
Back in the days of massive parts inventories you would be correct, however JIT has eliminated that issue.
Perhaps true -- but also the economics. Do you want to be a carrier or leaser, ten or 15 years from now, with a 788 to unload on the second hand market -- or a 789?
Boeing has just implemented changes to the 788 in order to make it more similar to the 789 production wise. This will reduce the cost of producing a 787-8 and makes it easier to increase the overall rate to 14 per month. This came together with an increase in new orders for the 787-8 starting last year, with AA ordering 22 the biggest one. There have also been some down conversions from the 787-9 to the 787-8, for example BA has done this
Did they ever make the 788 center box and gear bay (larger) to floor compatible with the 789? I had heard this was significantly different, at least in the past.
I still think upgrades to 789 are far more likely than carriers down-gauging to 788...If the 788 is now similar to the 789 production wise...you get 30/40 less seats for very modest decrease per-flight cost. It's the same reason A338neo is looking shaky and the A358 was never built. And is Boeing really going to price the 788 to make it worth your while?...Or more likely, price the 789 competitively...e.g. Hawaiian.
Sorry for getting a bit off topic !!