The response I got from Twitter DM is quite positive:
"This is a very recent update so we are still working with other airlines to determine what alternative we will be offering out of HGH. Alternatively, you may be booked right now out of PVG, which is 103 miles away from HGH."
It seems that there may be alternative partner flights out of HGH (HGH-TPE-SFO, I am looking at you) to be rebooked on at a later date.