In the past 5 years I have made a bunch of money on airlines. One of the things with airlines is you do not have to guess what is going to happen. You can easilty check prices.
Checked American August 1 to London. From JFK best price is $992 rt. From LAX is 1402. Move to October and the price drop is $792 from JFK.
These are huge premiums to costs, the flight from JFK is like 5 hours. A typical domestic flught that length is $400. They are making huge profits on London flights and with lower hotel prices demand will only go up.
Not sure on taxes, I would estimate fuel cost for a rt at $150, down from $350 two years ago. I was wrong on the flight it is more like 7 hours. Still looks like these are very profitable routes. And demand will only increase