A modern regional turboprop could really kill it ten years from now. If emissions really start making a difference to the ticket costs. Sweden and Finland are a

A modern regional turboprop could really kill it ten years from now. If emissions really start making a difference to the ticket costs. Sweden and Finland are already introducing such measures. There's a lot of room for more efficiency. With carbon wing spars you can have whatever aspect ratio is practical for operations with not much weight penalty. In the last decades, the wind power industry has pushed forward methods for large composite structures mass produced cheaply. Boom can always pivot. From Concorde came Airbus as well.