There seem to be 2 facitons here.

One set thinks we have the techology to create a new SST and one set thinks we do not.

I think we don’t have that technology yet. Can anyone seriously tell me that they think a new SST can be developed, which has the non-speed capabilities (range, fuel burn, capacity, noise) of a 767 or A330 whilst still costing no more to develop than any other new aircraft? If we had, why has no one developed it? They’d be trillionnaires over night!