I wonder with all this hub-bub about SEA and Delta and competition, if people have looked at the bigger picture.
SEA is the 6th largest O&D market for Asia/Oceania in the US. Honolulu is the 4th largest, so you can largely ignore that since that's completely different from the lower 48, with the other 4 being LA/NYC/SF/CHI, respectively. SEA's fastest growing population is the Asian population. Delta is 100% here to stay for TPAC, there is no other better Asia gateway remaining because the others are either controlled by UA or have too many other disadvantages like distance for NYC or competition at LA.
Yes, SEA will probably never match SFO in size for UA's TPAC OPs, even if the SF metro continues to shrink and SEAs continues to grow. The only other top 10 demand metro in Delta's network is BOS, which is completely unsuited to be a TPAC hub.