Launched at the Paris Air Show, the 737-10 will be the airlines’ most profitable single-aisle airplane, offering the lowest seat costs ever.

Design changes for the 737-10 include a fuselage stretch of 66 inches compared to the 737-9 and levered main landing gear. The airplane has the capacity to carry up to 230 passengers.
Other changes include a variable exit limit rating mid-exit door, a lighter flat aft pressure bulkhead and a modified wing for low speed drag reduction.

Seen here is a rendering of the airplane.