[cmdrriker]

Unless some government(s) steps in and dumps a ton of money into SST development and production nothing is going to happen.

The Concord showed this by shouldering the burden of research, development, prototyping, and then production. Turns out SS's don't have the load factor & associated economics to make it a viable mode. That revelation was before environmental and political challenges made those economics worse.

Unless unobtanium can me mined, tooled, and manufactured cheaply into airframe parts and power such as scram-jet or super cruising turbofans can push a plane at Mach 2 with 200+ seats behind the pilot, methinks its just a pretty artist's conception on a Pop Mechanics or Science magazine cover.