>Given the choice between flying NYC-London for $1000 in 6.5 hours versus $2500 in 3.5 hours, 99+% of people will choose the first option each and every time.

Two counterarguments apply here:

-This may not hold true for very long routes, like LA to Tokyo and other trans-Pacific routes. Not spending 11+ hours stuck in an airplane is certainly a luxury many would pay a premium for.

Concorde could not fly such routes as it lacked the range, mostly due to its fuel inefficiency, which brings me to the second point:

-Those new proposals promise much higher fuel efficiency than Concorde. Granted, it's still nowhere near regular subsonic airliners, but still far below the figure shown in the plot above.

Does this mean they'll be successful? No, absolutely not. There are still major technical challenges they need to solve, and even if they do, it is unclear the aforementioned gains compared to Concorde will be sufficient to make them commercially viable.

Overall, I believe they are still more likely to fail than succeed.

But it is certainly not a guarantee.