Originally Posted by
ronin308
They did, it's called the 777x.
The 747-8i was an attempt to evolve the design to modern specifications but there's only so much you can do with 4 engines. The 777x will have offer a plane that carries almost as many passengers (it has a longer wingspan and fuselage than the 747) but for significantly less fuel for seat mile.
The 747 is like the equivalent of a Ford Model T. An outstanding technological feat and breakthrough for its day.
Even the past decade the cost of fuel efficient machinery is coming down. We see this in automobile mileage efficiency. The cost is coming down for fuel efficient engines for planes, so it's just a matter of time until 747 is obsolete, as it will no longer make economic sense to purchase these gas guzzlers.
The key economic indicator for successful airlines is fuel.. as fuel is the largest cost for airline operations across the aviation industry.