TS
The OP was asking about a 'Low-Cost' Long-Haul Airline, and most of the suggestions made seem at first sight to fly in the face of the Low-Cost model.
Indeed, including most of what the OP stated in their OP!!!
The next major move in the airline world is to claw it back to being profitable. That means consolidation of the old players into the new ones and other oldies seeking comfort with each other. If they get it right then they can drag prices back up. THEN there is an opportunity for a low cost LH model to be tried. Except that it has been tried before . Mostly, what works is the middle ground with a carrier having, 2, 3 or 4 class a/c to the same destination. The all-cheap and all-expensive work in only narrow circumstances.
Perhaps some of the carriers that fail will try to do LoCo in LH but I doubt it because, once they fail, the a/c are in the control of the financing companies and they make the decisions.