swh,
The A359 regional is the exact same airplane as the A359 (long haul). All Airbus is doing is reducing the certified MTOW and lowering the price. I'm not sure how that changes the fuel burn on regional flights. Please explain that...
Wrt A339, the airplane is gaining weight. The A350 style wing extension and winglet increases weight. Right? With regard to the NEO engines, the Trent 7000 will be based on the Trent 1000, which weighs a tonne more than the Trent 700. So that's two tonnes more weight plus the weight of the winglets and extension. Based on those numbers, the break-even is indeed between two and three hours depending on payload.
Let's keep in mind that the A339 still has an eight-abreast, 1970s era fuselage and a 1990s era wing and empennage. So, if you think that competes against a 787, I have a bridge to sell you. It's big and red.