Out of necessity during the pandemic ANA and JAL made themselves much more competitive for SE Asian routes, taking a lot of Thai Airways business for instance, and it seems they've realized that works well for them, and the large number of customers who've discovered the quality of those carriers. While UA and AA also participated in the Japanese through routes, they both relied on connecting flights from the Japanese carriers, who are likely no longer interested in sharing their constrained capacity to the final destinations. This leaves UA only North America to Japan demand, which is minimal.

Unfortunately for fliers to/from Japan, the days of "protected", thinly populated premium cabins are over, as travelers paying 40% less (than to destination TYO) to fly further afield are taking up the (formerly unprofitable) slack.

Ironically, this may very well push more Japanese customers seeking to avoid the tourist hordes to the US carriers, assuming they can provide some semblance of the Japanese carrier soft product.