There's a lot of non-stop flights that are currently possible to fly with the aircraft available on today's market, but are not offered simply because they wouldn't be profitable. One can obviously think of many examples.
On the other hand, there are a few non-stop flights that cannot be offered by today's aircraft, but that would (probably) be profitable if and when technology is able to deliver. There aren't that many city pairs that would justify the development of a new aircraft with a range even bigger than the A340-500 (and soon the 777LR) - let's face it, with these planes you can already cover almost
the entire world. But let's think, which would those city pairs be?
Most of these are Australia-related. Most other places on the planet can already cover any destination with today's planes, and certainly any commercially interesting destination.
There might be more cash-cows that I haven't thought of. But it's a niche market, as the A340-500 and the 777LR already are.
And there's of course the shorter flights you can operate with less weight restrictions. That might actually be a better argument than those ultra-longhaul flights.
I scratch my head, therefore I am.