Just a small aside.
The Boeing machinist strike is over (barring a really strange move and the members vetoing the overwhelming recommendation from union leaders to accept the offer when they vote on Saturday.)
Boeing Strike Over—What Comes Next? | After a 52-day strike, the International Association of Machinists and Aerospace Workers (IAM) and Boeing reached agreement on a new contract that will run for four years instead of an expected three years | Oct
The strike lasted less than two months. I think it safe to say after bleeding red ink Boeing will be throwing extra resources (shifts, manpower, etc) at restoring production to pre-strike levels, or higher if possible. Therefore I would suggest that the B777 upgrade timeline - whatever it may be - would only be extended by the fairly minimal two months.
This is of course outside of any other factors such as lack of trainers, continued worsening economic conditions, and the like. But just my humble opinion that the strike will prove to be one of the lesser factors due to it's relatively short duration.