It seems Airbus is launching a stretch A350-1000 this summer. To reduce the gap between the A350-1000 and A380-800 a bit.
Probably giving in at payload-range a 10t MTOW increase is expected..+40 seats.
Exclusive - Airbus touts 400-seat 'A350-8000' jetliner | Reuters
It seems this higher MTOW decision was taken in 2010 already when they decided to give the -1000 a bigger wing, new landing gear and up a new to 100klbs RR XWB engine version.