It seems they could fit 3 and 3 seating in that lower section. Plenty of room down there. Windows would be problematic. But if they put in a low-cost "Galley Slave" class, I'm sure a lot of people would take them up on it.
But that's the entrance to the plane. First class and business class passengers will either turn left or go up the stairs while economy passengers will turn right. There's got to be quite a bit of room to handle up to 479 passengers boarding. One of the options will be galleys in the currently unused crown space above the economy section. This will allow another 12 economy seats.
It seems they could fit 3 and 3 seating in that lower section. Plenty of room down there. Windows would be problematic. But if they put in a low-cost "Galley Slave" class, I'm sure a lot of people would take them up on it.