The A350 XWB has EASA ETOPS 370 and is looking for 420+ in due course, the US FAA has given it ETOPS 180+ but then the bad dream with the Trent had 330 ETOPS but the FAA has cut that back to 140... The 787 was late because it was all new incl composites and the 777 is a development of an existing aircraft... but Airbus can get it wrong too look at the sales of the 340 and 380 four engine frames vs the twins which is why the 350 is being pushed but either way it’s a big call and a pivotal one