The KE route was a tag-on to IAD, not JFK, if I recall correctly.
Boston has really spiked, and it all started with the JAL 788 in 2012. That plane (and others in its general class) made opening Boston much more feasible. Of course, the robust and rather 'stable' socio-economic demographics in the Boston metro area are probably an even bigger reason why.
It's interesting you say that about the 788/9 and that has driven a ton of growth, if you think HU with their 2 routes, KE, DY, BA bring it from time to time along with VS, it certainly has had the versatility to handle many routes, however I am just as impressed at the use of 77W's and the like and of course next year we'll have 3 388's plying LHR, MUC and DXB for at least the summer season, plus let's not forget the multitude of 330's.
Next week Mrs VS is off to PHL for the week, so I am going to have time to finish my 2009-2019 international analysis where you will see a lot of the above come out, I've already done Europe separately, but figured adding ROW will show just how far we have come.
if we hark back to the heady days of 2012, we did a grand total of 4.3m pax for the whole year
Caribbean - 761K
Canada - 614K
Europe - 2.9m
Asia - 79K
compare that to the latest numbers for September YTD 2019 and of course, still 3 months to come on top of this.
Caribbean - 1m
Canada - 761K (and this is with the big reductions by WS)
Central AM - 270K
Europe - 3.3m
Mid East - 532K
South Am - 82K
Asia - 458K (let's reflect on that growth for a minute, compared to JL starting up above)
Africa - 17K
Total: roughly 6.5m with 3 months to go, last year we did roughly 1.6m in the last 3 months of the year, so we are going to fly (pardon the pun) past 8m..
so in 7 years, not quite doubled... but that's some scary growth and once E is finished and with the growth from B6 and DL and others to come, I am sure that 10m is quite possible.
That feeling when you sit at the end of a runway, brakes are released and the raw power takes over. Now that is a thing of beauty and it never gets old.