Not really. Some of the passengers already purchased their tickets a year ahead of time due to the rising of ticket prices on SEA/TPE-NA routes (and Seattle was a monopoly then).

The announcements for DL were announced last December and CI/JX launch rumors started in the same month, so I would expect EVA's price to drop after Christmas break. All other carriers will face intense pressure the month all the airlines launch their operations. If JX decides to make Seattle daily by Christmas, then there will be even more capacity (covering more than BR's 3 weekly flight that's likely not coming back).