As markis10 pointed out, JQ's 78*s will have a 3-3-3 configuration in whY.
Yet Japan's ANA (NH) has only 2-4-2. On NH, seat pitch is 85 centimetres while seat width is 46.5 centimetres.
I could not find what the exact cabin width for a B788 is (although one site implied it was 18' v a B773 at 19'3' in the old scale), but apparently it is narrower than the B773's 5.87 metres. The B773ER on some airlines is still nine across if I recall, but others have long gone to 10 across seating in a 3-4-3 configuration.
How are increasingly overweight Australians and other Westerners going to cope with what appear to be very narrow seats on JQ for a nine hour 50 minute trip to HNL or a trip to HKT? The average age of Australians is just under 40, an age when many of us stack on a few extra kilograms.
While many will put up with uncomfortable slimline seating to save some dollars on the airfare, this may be a downside of the new aircraft that many Australians and other potential travellers are yet to realise.