Airbus seems to have problems getting the A350 production ramped up. They seem to fall short of scheduled deliveries this year.
Looking at where both Boeing and Airbus are going in the next few years, it seems Boeing will fight the new A350s in the middle of the segment with their 787-10, 777-8 and 777-300ER.
Lufthansa says the 787-10 doesn't go far enough at MTOW, the 777-8 can, but is very heavy. The 777-300ER is an excellent aircraft, but seems questionable investment for the next 25 years.
Does Boeing need something new for 300-350 seats / 8000nm (passengers only / still air), the middle of the market?
The 777-200ER and -300ER ruled that segment for the last 15 years.