The Airbus competitor to the 767 is the not the A350, it is the A330, which is ubiquitous outside of NA in the medium haul market. It has been an extremely successful plane for Airbus and will likely continue to be so with the A330neo.

While each company's offerings overlap somewhat, the A350 is a substantially larger plane and competes with the 777.

Widebody twin 2-class capacity (variants):

  767  | 216 / 261 / 296
  A330 |       246 / 300
  787  |       242 / 290 / 330
  A350 |                   325 / 366
  777  |                   313 /     / 396
  777X |                         365 / 414