Right, office chatter ... only slightly less believable than galley chatter, but right down there with cockpit ditto.
But let's look at this logically, as in where will EK be at around the turn of the decade. If the A350 doesn't fit with EKs plans, and they have already ruled out the 787 for being too small, one then has to accept the proposition that EK sees no use for an aircraft with less than 400+ seats. That's not a plausible scenario, frankly.
The A350-900 is likely to be the smallest aircraft in EK's future fleet, seating around 275-300 pax. Next up is the -100 with around 350-375 seats, then the 777-9 with 450 and finally various versions of the A380 with 500+ seats. That seems mighty logical to me - using the A350 to build up new routes or add frequency, then progress to the John Deere NG or the Whale as the market grows.
Starting a new route to, say, Oslo or Prestwick, with a 450 seat 777 is a bonkers idea - EK has historically had a lot of success building up a new route with the A330, then moving to 777-200, 777-300 and A380. Why would that formula not work on the other side of 2020?