This would also be helpful for culling trains from the network once their home outpost is dry. Have them proceed to a holding yard if they go without gaining any items at the stop over the specified amount of time and then wait until full. No inserters at the holding yard will make them wait there for the player to manually re-assign them. The refueling station jump would also be incredibly handy in keeping a fleet of trains supplied.OpenTTD has a thing for this, it's called "Conditional Order Jump" - an order that, when executed, checks the train's condition and decides whether to continue on to the next order, or rather skip to a specific order.
You could essentially make a long-range logistics network out of this. That would be pretty amazing.If stations gets circuit connections, it would be interesting to have them being able to be enabled/disabled from circuit conditions. It would permit to have train not going to disabled stations.
One other thing I would like to suggest while trains are getting some love: the option to switch trains over to visiting same-name stations in a round robin fashion rather than the closest one all the time. Another useful option would be to have them visit the nearest/round-robin unoccupied station so if I have three trains delivering iron to 6 stations all named iron-dropoff, they can simply visit choose ones that aren't currently being served and have not been visited in the last trip or two.