If the right of way is fully separated and well-fenced, as with automated (yes, like BART) transit, then certainly the dispatcher can "run the train". That's because the dispatcher simply provides movement authorization and the train itself (the computers onboard and wayside) do the work. Yes, engineers and conductors can be replaced. Your point about the inevitable foulups is real, of course; even BART has problems occasionally ;). Arguably, there might be a need to reopen some section camps as bases for the cleanup and MOW/MOcomputer crews, of which more will be needed.

That said, I don't think the legal system in the US would permit fully automated operation if there is a realistic chance of trespassers and grade crossing wrecks. And if you have grade crossings there will be wrecks. At minimum, you would have a BART-like thing where the engineer becomes a train monitor whose main job is to stop everything if there's an emergency the computers can't handle.

Don't you hate all those Press articles where the engineer is called the "conductor"? As automation proceeds, that term might become more appropriate.