Just see what happens after implementation of LROPS in early 2003......I expect many airlines would switch from B777 to A340 because A340 of quad engine design has longer permissible diversion time (up to 8 hours for LROPS compliant ones compared to 3 hours for B777), hence enables more direct routing, like routes over the poles, while still maintaining maximum safety for the passengers (no need to land at polar airports with poor facilities.)

And the Sonic Cruiser you mentioned is twin-engined, so it is still subjected to ETOPS constraint like B777, hence only longer routes not going via extreme areas can be used. It would still be slower than A340 on flying routes like trans-South Pacific, trans-South Indian, trans-South Atlantic, transpolar routes.