Firstly - I'm not in the biz, as the name says I sit somewhere down the back.
Blimey no wonder the shape of aviation hasn't changed since the '50s. With all the negative feedback and no one willing to even look at concept is it hardly surprising that aviation design is virtually stagnant.
There are many reasons for this and the first three are
Money ,
Money and
Money. The cost of development means that only consortia can really put the funding together. You then have the problem of consensus. The only point on which companies (i.e. individuals) will agree, is that they want to make money. This is for the simple point that, if they do not, no one will have jobs any more!
Boeing 'bet the farm' on the 747 and they won, but the machine was an enlarged 707. Sure, there were many, many differences but the basic profile of circular fuselage, wing + podded engines, was the same. What they managed was the leap in size to wide body and so forth. Boeing nearly closed because of that. No one is going to make that kind of decision again.
I am sure that there
are some new designs waiting to be hatched but they will not emerge from commercial aircraft companies.
Where might they emerge from? The military do not have the budgets for 'blue skies' ideas that they had 20 years ago. They have to concentrate on getting bombs to specific points and (almost) all development is focused on that. Getting the bombs to the place of explosion is to be on unmanned devices wherever possible.
There is no market for a new Concorde, there is no market for anything that will not get it's money back
without fail. It is said that a new commercial jet transport, has to sell at least 300 hulls to get back it's development costs (I sit to be corrected on that number).