This was posted originally about 2 months ago. The fare has been valid ever since. I bought it 2 months ago for my October vacation to Bali (getting a flight from PEK to DPS using miles). I was able to get through DTW (and therefore A350 both out and back). On certain calendar dates you can still find this routing. You just have to play with it.
See?
https://www.delta.com/cart/activity/...ho&itinSegment[0]=0:F:BOS

TW

L:761:SEP:19:2018:10A&mkcpgn=MS_GFSR _DESK_INTL_TR_DL_140414_GFSDESK_US&itinSegment[1]=0:Z

TW:PEK

L:189:SEP:19:2018:01P&paxCount=1&cur rencyCd=USD&itinSegment[2]=1:Z:PEK

TW

L:188:OCT:03:2018:04P&itinSegment[3]=1:F

TW:BOS

L:2971:OCT:03:2018:07P&numOfSegments =4&cabin=BU&exitCountry=US&vendorID=Google&vendorR edirectFlag=true&tripType=roundTrip&fareBasis=ZLX0 3PDA:ZLX03PDA:ZLX03PDA:ZLX03PDA&price=2208.11
ATL