The 787 showed us that smaller aircraft going point to point is a winner. Qantas are supposed to be loving the yield on theirs, much less capacity than the 747 it replaces but this seat scarcity drives up yields massively.
So if it works replacing 747s with 787/A350s, why not in the single aisle market, so A321XLR replaces A330/B767 where possible?
I'll give a Northern UK centric idea on why I'd be happy to fly an Airbus over the Atlantic. I live minutes from Leeds/Bradford, but to go anywhere means traipsing to Manchester. I recently went to Belfast on Ryanair, had to be Manchester. Airfare was £10 each way, time about 60 minutes. But to get to Manchester I had to take the train to/from the airport, cost me £25 and took 2 hours each way! So doubled the cost of the flight and tripled the journey time plus necessitated changing trains etc. No if they went direct from Leeds/Bradford in a Cessna 152 I'd have taken it over all the faff of travelling to a gateway airport.
The future is definitely smaller jets doing point to point.
G