I had a similar schedule change, SFO-HKG-BKK, where my late pm flight was moved to the earlier flight. The confirmed Polaris upgrade carried over, but now have a 16 hour layover in HKG. Cant find anything better than a 4 hour layover then flying Hong Kong airlines, arriving BKK at 1:15am. Don't want to arrive at that time though. Think UA could and would move me to SFO-SIN-BKK on UA then SQ?