An unmanned aircraft will still need human's operating it, they just wouldn't be in the cockpit and they may be able to control more than 1 plane at once. However, because a human is in overall command it will be subject to human errors, just like in every cockpit today. in fact the risk of an accident is much greater because the human controlling it could be hundreds of miles from the situation the aircraft is in and therefore unable to make informed decisions in the way crew do today.
So, a Unmanned PAX aircraft will not happen in the lifetime of anyone who currently posts on this forum but you've all got to see that commercially there's a market for non-pax UAV's for obs, and cargo. or am I wrong?