NASA contracted industry design teams to design potential airliners for the 2030 timeframe. Some common design themes included flying slower (mach .70 to .75), higher (45,000 feet) and using very high by-pass ratio turbofans. Many of the design airframes were generally conventional in shape however the MIT design team presented a hybrid wing body. Their fuselage cross section is like two conventional tubes placed side by side to provide twin aisle seating. This permits the aircraft to have a lifting body nose and reduces the size of the wing and tail.
Here is the link to the three page article in Aviation Week