Rather, the 747 was largely the result of a request by Pan Am's Juan Trippe for a very large passenger aircraft....
That is what I recall. At the time Pan-Am was the largest airline in the free world and their order alone would have justified production of the 747.
There was another factor also that greatly benefited the 747, that of range. Pan Am had a number of very long air routes - US into South America and Europe, trans Pacific etc - and was looking for greater payload range, compared to the B707 (-320 3,700 miles). The 747-100 had a range of 4,600 miles, 747SP 5,800 miles and 747-200 6,500 miles.
Whilst the A380's 8,000 mile range offered a great improvement during development, unlike the 747 that for many years reigned supreme in long haul range, the A380 range was rapidly matched by smaller, more flexible and economical twins such as the Boeing 787 (7,400 miles) and now the A350 (8,400 miles).
I suspect a viable limit of commercial passenger aircraft range has now been reached, at 8,000 miles/17 flight hours/one third Earth circumference. Any increase in aircraft range without being matched by a comparable increase in aircraft speed, could prove very unpopular with long haul passengers.
But who knows? The concept of todays air travel and aircraft capability could not even be imagined when my father was born only 6 years after Richard Pearce and the Wright Brothers first flew!