One important limitation not covered here is the height vs width of the airframe.
If the internal cabin is to be high enough for passengers to walk around, the wingspan must be much larger than that of conventional regional airliners that carry 100 or so passengers.
At that point, you might as well add more rows of seats.
Its likely we will never see a regional airliner or charter plane of this design for this reason, mainly just international flights where you can sell the extra several hundred seats.
If the industry is forced in that direction, they will have to compensate by scheduling less frequent flights to fill the seats.