Just picked this up from PPRuNe BHX (sorry if its been posted earlier but couldn't find it)
"Emirates winter 18/19
The lunchtime EK39/40 flight will be downgraded from an A380 to a B777-300ER from 7th November 2018
It is not known if this is permanent or temporary"

My four fights after this are still showing seat choice on A380 and dummy bookings for November & December are still showing A380 on all flights so perhaps the back room has not caught up yet

SS