Comment by jvm

To actually answer your questions:

- Noise means you can't do US domestic

They don't seem to be targeting this.

- Concorde didn't have the range for Pacific

They do seem to be attempting Pacific range.

- Costs didn't work for Atlantic routes

They are trying to bring down costs considerably.

- And airlines want lots of identical planes, not one special one for one route

This will certainly be a drawback, although if they could take e.g. 50% of premium transoceanic it won't be so specialized.