It's very difficult to design a quiet supersonic aircraft that's also fuel efficient.
The AS2 will carry max. 12 passengers yet it is nearly as long as a Boeing 767, with a very thin and long fuselage.
This type of design might scale up a bit, to around 20 passengers, but going beyond that will require many new technological breakthroughs.
A decade ago NASA outlined some goals for a "next next generation" (N+2) quiet supersonic aircraft capable of carrying 35 to 70 passengers at Mach 1.8 and a 4,000nm range.
The idea was to spur research and development activities for new technologies required for such an aircraft by 2020, and to enable an even more advanced N+3 supersonic airliner with up to 200 passengers by 2035.
However, analysis led by Boeing and partners a few years ago concluded that it is unlikely we will have the technology for N+2 by 2020. Indeed we will be lucky if the Aerion AS2 (considered an N+1 aircraft) or a competitor actually enters into service by 2023.
So for right now, only business-jet sized aircraft looks realistic given the environmental constraints.