I'd say besides the teleportation technology, the space travel is the way to go
for long haul travel. Hopefully we will get the aircrafts that can reliably carry
passenger across the globe over the outer atmosphere within a few decades.

In the limit of high Reynolds number (a dimensionless scale parameter for fluid flow; all aircraft are at high Reynolds number so that they experience turbulent flow), drag increases with the square of velocity increases. 10% increases of speed involve 20% increases in fuel operating costs. It gets worse right around Mach 1.0, as other posters have noted. There's no magical technological bullet.

Going into the vacuum of space gets around this but the energy cost of going up that high is huge - again, not really a cheap solution.

With the exception of those who used to be able to pay for the Concorde, those who might be able to pay for superexpensive supersonic business jets, and fighter jet pilots, routine airplane flights will not go supersonic.

i thought some gulfstreams were speced at M .9 ?

Transcontinental Speed Record an Old One
 

Interestingly enough, the record for an east to west commercial flight was set in 1962. It is listed as one of the top ten records that the National Aeronautic Association would like to see broken:

Capt. Gene Kruse’s August 15, 1962 Class C-1 record for Speed Over a Commercial Air Route, East to West Transcontinental, set at 572.57 mph in a Boeing 707-720B. Record-setting pace must be a minimum of 578.30 mph.

With the need for fuel efficiency, it may be a while before that one's broken.

The Gulfstream V, including its current G500 and G550 variants, cruises at Mach 0.85 with a top speed of Mach 0.885. Earlier versions may have been slightly faster, perhaps reaching Mach 0.9 as a maximum, but I doubt their cruise speed was that high.

commercial supersonic flights will not happen for a while. the reasons are mainly those already summarised in this thread.

In addition to that, supersonic will cause higher fuel burn which would increase the emissions and thus higher environment impact. The latter is frowned upon and therefore no airframer would venture to to this area.

This would change when the available technologies will eliminate this downside.

gotcha :)

Could they break the barrier with less cost by going higher? I'm not educated on the physics, so just curious.

If I could go from NY to HK in 10 hours instead of 15, I think I could convince the company a reasonable premium can be justified, for example.

On a side note how about alternative fuel engines for planes? Of could you see electric now that would be interesting but probably highly difficult to achieve.

Batteries have a weight-to-energy ratio of 10-100 times worse than chemical liquid fuels. We won't see battery-powered airplanes except as curiosities. Now biofuels might be a possibility, and I remember reading something about some demonstrations planned...

Why no faster airplanes?
 

Three words: Cheap Ticket Prices

Keep in mind that the airplane might be traveling at a specified speed but the localized airflow over the wing will be faster (bernoulli effect) so the plane might be near supersonic while the airflow is supersonic. As others have said, there is a huge penalty for every step in increase in speed.

Citation X cruise at IIRC Mach 0.92 which might be the fastest transportation jet.

Boeing had plans for but then but canceled the Sonic Cruiser
http://en.wikipedia.org/wiki/Boeing_Sonic_Cruiser

Which was supposed to fly faster but still subsonic.

Concorde got from LHR to SQ in 9 hours, compared to 13 hours by 747.

Problems? One, fuel cost. Concorde burns the same amount of fuel on the same route as 747, but carries 4 times fewer passengers.

Another, this 9 hours included fuel stop in Bahrain, while 747 was nonstop.

Note, I am not saying you could not do slightly better than Concorde.

Concorde has 185 ton MTOW, 79 ton OEW, 12 ton max payload. So, it burned about 94 tons fuel - slightly over half MTOW - and the payload was just 13 % of the rest. Range 6200 km at that payload.

Compare with, say, 767-200ER!

MTOW 179 tons. 82 ton OEW. 35 ton max payload. So, at max payload, it burns 62 tons of fuel, payload of 30 % of the rest. Range over 9000 km at that.

Now, L-2000 and B-2707 were supposed to have about 300 tons MTOW, burn about 140 tons fuel at a range similar to Concorde, and have payloads of over 30 tons. Was it feasible? Maybe, maybe not. Is if feasible? Probably yes, you could build a SST which carries say twice the passengers of Concorde without burning twice the fuel. Still much more than a subsonic jet with comparable payload - you cannot hope to get similar prices.

Is it waste of fuel? Sure. But subsonic business class is waste of fuel, too. Maxjet and Silverjet both fly 767-200ER with 102 business seats. It certainly burns less fuel than 100 seat Concorde. But each passenger on a 102 seat Silverjet 767 burns more fuel than on a 255 seat 767 on the same route!

Can you afford it? Seems to be getting more popular. There is Eos with 757, there is Privatair with 767-300ER (just 50 seats - 38 at 4 abreast and 12 at 3 abreast)...

Would it make sense to spend the money on crossing faster rather than more comfortably? If you had a choice to spend 8 hours on First Class or 4 hours in a cramped Concorde, what would you choose?

Up to 4 Hrs, I can probably deal with the cramped seats but there is also
a factor of the time on the ground:

Check-in, Immigration, boarding, taxi-take off - air time - taxi to the gate -
deplane, immigration, baggage collection etc.. etc.. With the current security
screening mess.. you waste a lot of time on the ground. Saving a few hours
in the air won't make a significant difference over all... so whats the point..