Boeing appears to be aiming to reach a decision about the further development of its 777 programme during the second half of this year.
Speaking at the Aerodays 2011 conference in Madrid, the airframer's chief technology officer John Tracy said that a decision on how the long-range twinjet would be updated would be made "quickly" after determining the company's future narrowbody strategy.
Whether the current 737 family is to be re-engined or replaced with a clean-sheet aircraft design will be decided in "the next few months", he says.
One of the potential avenues for an updated version of the 777 line is to replace its aluminium wing with a composite structure.
Another option is to pursue a completely new successor, as the aircraft family faces increased competition from the Airbus A350 XWB.
Airbus maintains the baseline A350-900 will enter service in 2013, with the -800 and -1000 variants to follow in 2014 and 2015 respectively.
How Boeing will further develop the 777 programme depends on the available engineering resources, says Tracy, and this can only be decided once the future of the 737 is clear.