There has already been a narrow-body aircraft that can fly transatlantic routes for quite some time: the Boeing 757. In fact, American operated 177 of them until they were retired early in 2020 due to Covid (according to https://en.wikipedia.org/wiki/American_Airlines_fleet; video of a Dublin-Philadelphia flight: https://www.youtube.com/watch?v=U1OIdiKgqrA), and now intends to use the A321 XLR for the same role.

United inherited a bunch of long-range 757s with the Continental merger. I flew one Newark-Stuttgart one summer. United saw it as a cheaper way to fly transatlantic with a smaller crew.

Problem was that the aircraft couldn't make it back to the US on a single tank of fuel if the jet stream was too strong. Which happened a lot. So we got a nice detour to Goose Bay for refueling and nearly missed our connection. The regulars joked that YYR was the new United hub on the east coast.

I don't think UA does this much anymore. Maybe COVID killed that route too.

fuel burn, and CASM by proxy, on the a321xlr and 7m10 are much better though many pilots love the takeoff performance of the 757.

check out how they compare here: https://www.aviatorjoe.net/go/compare/737_MAX_10/757-200/

the 757 was the best narrow-body long-haul capable jet of the time (and it was the only one of its type that could fly LGA) but more fuel-efficient engines will do to it what the 787 did to the 747.

I took a narrow body 757 form Paris to Newark back in 2010. Airline long since defunct. BA used to operate a business-only A318 from New York to London from 2009 until covid too (due to length of City runway had to stop at Shannon on the way to New York)

Did you use an LLM to write this post? The Wikipedia link is hallucinated