Already there?
Between those city pairs where there is enough passenger traffic willing to pay for it, there are already nonstop flights.
These cities are usually hubs.
Hubs are usually located, with some exceptions, in metro areas with enough population and enough wealth to make a wide range of destinations profitable.
In the US, major hubs for overseas flying are located in New York, Dallas, Chicago, Detroit, Miami, Los Angelos, San Francisco, Atlanta and the like.
Note that these are all large metro area, and have significant numbers of well off folks, as well as significant business operations which may require that employees travel far and wide.
Now, if I am an airline, I might find it economically desirable to operate an aircraft larger than what local demand requires, and fill it by bringing passengers in from the hinterlands on CRJs and ERJs and even turboprops.
This is, of course, a hub and spoke operation.
Our little home airport (DAY) offers one stop connections to a large slice of the world.
It will never offer the nonstop flights of a JFK, ORD or ATL, since the wealthy population base to support such service doesn't exist.
Those who wish to fly overseas and can afford to therefore have to connect somewhere, which I have never found to be a major issue in our travels.
The future began more than twenty-five years ago, and it is hub and spoke.
ULR nonstops will never be more than a curiousity.
I myself would not like to sit on a plane for more than eight hours at a stretch, but that's just my preference.