Boeing expects orders for the 787 Dreamliner to be evenly split between the -8 and -9 variants, as airlines lean towards the bigger and more efficient variant.
Around 70% of the existing orders are for the -8, but Boeing expects the weight to shift towards the -9 in the long term.
"Ultimately, it will be around a 50-50 split," says Boeing's VP for marketing Randy Tinseth. With a 280-seat capacity compared to the -8's 240 seats, the -9 will be an aircraft with "absolutely fantastic economics", he adds.
In comparison, the -8 will be ideal as a replacement for 767s and Airbus A330s, and will allow airlines to enter new markets as it has a longer range than existing aircraft in the market, he adds.
Responding to indications that the 787-9 could be a replacement for the 777-200ER, given the similarities in the two aircraft's specifications, Tinseth acknowledges that the two models are "about 20 seats apart in terms of capacity".
"The airlines that already have a large fleet of 777s, if they need a 300-seat airplane, they are going to buy a 777. If you have committed to the 787 or you have not yet committed, you are probably going to sway on the side of the 787-9," he adds.
This is as Boeing expects future demand for its 777 passenger jet to centre around the -300ER variant as airlines seek to replace older high-capacity aircraft. The market for the 777-200ER will be "relatively small" going forward, says Tinseth.
"The core of the demand we'll see around the 777 will be around the 777-300ER as airlines replace older equipment as they grow. There's been a natural scaling down of size, the 747s are leaving the market," he adds.
Only a "handful" of 777-200ERs will continue to be added to the market, while the -200LR will continue to appeal to airlines operating niche long-range city pair connections, says Tinseth.
Boeing, however, expects sales of the 777 freighter to pick up as the cargo market continues to recover, he adds.
Sales of the 301-seat 777-200ER are flagging, compared to the similarly-sized in-development Airbus A350. Since the A350 XWB programme was unveiled in July 2006, Airbus has won 558 firm orders for the type, including 325 orders for the 314-seat A350-900.
In comparison, Boeing netted only 15 orders for the 777-200ER during the same period.