People will die because there is no guard on board?
Yes. It's only a matter of time.
There's the possibility of more than enough going wrong to need the combined talents of both driver and guard to prevent a serious incident becoming a multiple fatality incident.
A derailment at a junction will require multiple lines to be protected, if you've caused an OLE dewirement or damaged the third rail, any evacuation will need to take into account the possibility of live lines. It could be a bridge, washed away by flooding, damaged by a bridge strike or your own derailment.
Evacuation might be unavoidable - maybe you've ripped a fuel tank or the transformer open and there's a fire started underneath the train, maybe sparks from the third rail or from a hot exhaust has set the embankment where the train has come to rest alight.
The driver can't try and stop another train coming along at line speed and evacuate his train at the same time, passengers can't be left to evacuate themselves if there's track missing, live electric in the area, a fire ongoing or the possibility of another train coming through the section at high speed.
The incident has got a whole lot worse if the GSM-R radio set(s) have stopped working, as we now know is a very real possibility.
That's all assuming the driver hasn't been incapacitated. That's assuming the driver's cab didn't hit a bridge parapet, OLE mast, signal gantry or another train during the accident, and he's not either incapacitated or worse in the cab.
For me though, the biggest concern is increasing traffic - it's now more likely than at any time in recent history that in the event of a derailment with the offending unit fouling an adjacent line, it's going to be hit by another train. It's now more vital than ever before that a derailed unit is reported as quickly as possible to the signalling centre/box and lines blocked as quickly as possible.
That needs a driver and a guard.