It would be awfully nice if all the advanced engineering effort being put into multiple competing supersonic programs went towards working on lower emissions for the next generation of regular subsonic aircraft. If we can make a new subsonic jet for normal people that's at least 30-40% less carbon intensive, then that's something to get excited about.
Agreed on HSR though - here in Australia HSR has been a pipe dream for decades...
The desire for cost savings by way of using less fuel already means that huge effort is devoted to improving jet engines (and planes, the 787 is quite different than previous jumbos). Even after all that, slower planes are more efficient than jets.
Although there is obviously still effort being put into the supersonic programs, aerospace giants like Boeing and Airbus are working pretty hard to get a reduction in NOx, emissions and fuel consumption. We have gone a long way in designing a good aircraft, and have been making it more efficient over the last few years. One of the primary goals of these manufacturers right now is to become more efficient. [1] NASA has some mid-term goals for 2035 in terms of emissions, NOx and fuel consumption, in terms of TRLs.
A lot of effort is in fact being placed in these areas. NASA has had the N+1, N+2, etc., programs. There is a lot of interest in distributed electric propulsion (see the ESAero work), and Europe is working on their Clean Sky programs which are actively trying to push what is now called "Open Rotor" propulsion technologies. What is missing is major civil airframer (i.e., Boeing, Airbus) commitment to take some risks with new concepts that go beyond traditional tube-and-wing. Unfortunately, the outsourcing disasters that happened with 787 have convinced Boeing management that they "took too much risk" with the 787, conflating programmatic and technical risk, and it's hard to be sanguine about Boeing prospects for going beyond traditional configurations.
Agreed on HSR though - here in Australia HSR has been a pipe dream for decades...