It sounds like pure fantasy.

Boeing sees the day coming when you board a plane in New York and land two hours later in Shanghai, China.

"I think in the next decade or two you're going to see them become a reality," said Boeing Chairman and CEO Dennis Muilenburg.

Boeing expects hypersonic jets, flying at up to Mach 5, or 3,800 mph, could serve a small but important market of travelers willing to pay a premium to reach far-flung destinations in a fraction of the time it usually takes.

For example, a commercial flight from New York to Shanghai currently takes about 15 hours.

On paper it sounds great. In reality, the costs of operating a hypersonic commercial airplane means it may never get off the ground.

"It's hard for me to see, at least in the next 15-20 years, that it's going to be so cost competitive that it's going to compel the airlines to take a stab at it," said John Plueger, president and CEO of AirLease Corp.