I think the real comparison here might better be 787/A350 versus 767. In the end it is economics of fuel burn/maintenance costs and longer range versus interest/lease payments that will convince airlines to look at one or the other. As a few airlines introduce the new aircraft, I think they will win over the more discerning passengers, who are often also the most lucrative. This will force others to follow suit.

There was a huge cheer on the AC board when they announced the purchase of 777/787 followed by 20+ pages of frustration when the pilots killed the deal.

From what I've seen/read it looks like the 787 has the edge in operating economics and likely passenger comfort but Airbus will likely be cheaper thanks to lower development cost.

All else being equal, I'd rather fly the 787 than the 350 and certainly over a 767! I hope to be able to cheer loudly once more when AC's pilot union settles their petty (albeit not to them) internal squabbling over seniority rights from their merger/acquisition of CAIL 5 years ago and agrees on rates/rules for the new birds.