Is the MOM airliner single aisle or twin aisle?

Boeing is arguing this out internally right now.  MOM is Middle of the Market in case you had not heard.  Single aisle is a smaller jet liner say 180 to 200 seats.  Twin aisle is a substantially bigger plane, say 250 - 300 seats.  Right now, 2015, the airlines like smaller planes, and more frequent schedules to capture as many passengers as possible.  If they offer 3 or 4 departures a day of a smaller airliner, they are more more likely to all the passengers to be had on that city-pair.  If they only offer one departure a day of a bigger airliner, the passengers that want to depart earlier or later, are more likely to book with a competing carrier. 
  On the other hand, should over loaded airports like La Guardia impose departure limits (you airline so-and-so only get so many departures from here) then the airlines are likely to fall in love with bigger planes.
   Boeing is doing bet-the-company forecasting right now.