It'll be interesting to see if they still can design and build a new ground-up airplane design. The last all-new design was the 787, initiated in 2003 and launched in 2009, and its design was fraught with problems. Before then was the 777 in the early 90s (pre-McDonnell takeover), and the 757/767 in the early 80s. There's a phenomena that ofter occurs with large organizations where once their markets mature, everybod…
The biggest tell will be just how over budget the development process becomes. Another issue in large companies trying to build something new is the scope creep which leads to committees and then decision by committee. If the folks leading this effort in Boeing are smart, they will keep the size of the team as small as possible. Maybe they will even hire some people back to lead this effort... assuming they can find…
Boeing already does that. The seat size and spacing is determined by the airline customer.