Today's letter from the chairman confirms it, you will be able to fly multi-crew ships solo, with npcs in all other crew slots:
"we decided that you should be able to fly a multi-crew ship solo, having access to the same management system seen on the HUD of any single-pilot ship. However, should you want to invite your friends along to help manage your ship, you could access additional crew support stations, giving you a little more control over the ships’ various systems"
I'm not sure if this will be good or bad, but it will definitely be interesting.
"we decided that you should be able to fly a multi-crew ship solo, having access to the same management system seen on the HUD of any single-pilot ship. However, should you want to invite your friends along to help manage your ship, you could access additional crew support stations, giving you a little more control over the ships’ various systems"
I'm not sure if this will be good or bad, but it will definitely be interesting.