From an article on the WTO Aircraft dispute, by law student Ron Kendler, in the Boston College International and Comparative Law Review (article starts on p. 253):
As history shows, this is not the first time that the two parties come to the brink of a trade war over LCA: the 1970s and 1980s saw periods of escalation followed by settlement, first through the Tokyo Round, and later through bilateral talks. In each instance, the GATT enabled both sides to air their grievances before negotiating a solution. This dispute has operated in cycles of interstate conflict followed by cooperation, none of which catalyzed a trade war. The DSM provides further reason to believe that this era is no different.
The entry of new competitors will also exert pressure on the two rivals to resolve their conflict, as delays will put the United States and the EU at greater risk of losing their market position. Granted, settlement will not eliminate new rivals. Rather, both sides will recognize that they are better served when they are not constantly at odds over subsidies, which only distracts them from larger issues.
Nor will a negotiated settlement necessarily provide a lasting resolution. As long as Boeing and Airbus exist, their home governments will find something to contest. As they face new competition, the United States and the EU may even intensify their use of rhetoric and legal mechanisms with regards to LCA; it will just be aimed at other states. They may even ironically find themselves, after thirty years of rivalry, on the same side of this hotly contested issue.