Interesting if this ever gets to built I'm assuming it would be attractive for very thin but long routes. Like a 175 to certain South American cities. But:
1. This thing would need to have proven economics
2. The acceptance of the a/c by the public. Would you want to be in a 175 for a six hour flight?
3. Cost of operation, including training costs
4. And of course the a/c actually needs to make it to market.