Maybe this type of automation could be improved by letting trains handle the long journey part:

Autonomous truck -> train -> autonomous truck

Then, the automated trucks (that could maybe be dispatched from rail networks when you have cargo to send) dont have to do the long distance part. Only the last couple miles each time from train to warehouse and vice versa.

I’m sure there are complications im missing, but at scale this sounds like a feasible plan.

For shorter haul trips though, trucks are necessary for the whole journey no matter what.