Twitter has an image of CX884 doing a 180 at the end of the runway at Shemya, in very low cloud/fog, before departing.
I was wondering if the 777 could turn around on the runway since the parallel taxiway doesn't go all the way to the end. I've often had PASY as an ETOPS alternate but hopefully will never land there.
One of the pictures on the Twitter link that you shared has a good picture of the 777 flaperon that is in the news on another thread.