More composites, more fly-by-wire, more advanced more computerized avionics, more automation. Tweaking and eeking ever more bits of efficiency out of engines and aerodynamics.
What I think you WILL NOT see is any major changes to the basic planform of commercial aircraft, anything radical like blended-wing lifting bodies, bit delta wings, canards, high capacity supersonic transports. Stuff we all see design sketches of, but never come to fruition.
If any of that would really pay off, we'd be doing it already.
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When the search for better efficiency finally overcomes the reluctance of passengers to accept anything but a "tube with wings" we'll see blended wing body designs. That's pretty far off in the future though. Even the most amazingly high tech commercial aircraft today is a moderate evolution of the good old 707.
For business travel, faster might actually become a reality. Gulfstream is working slowly towards that goal.
http://savannahnow.com/exchange/2014-08-18/gulfstream-moving-toward-supersonic-jet
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I don't think "passenger reluctance" has much to do with it. It's just the simple engineering challenges of pressurizing anything but a "tube with wings". And if you make a tube inside the lifting body, then you've got duplicated effort in terms of mass and weight for the outside aerodynamic shape, vs. the pressure compartment inside. Granted, there is resistance to losing windows etc. or ever longer rows with no windows, but then the super wide body planes like the 747, and the A380 wouldn't have succeeded already if that was the case.