A good feature would be new industries that pop up here and there on the map. Conversely, industries that close down may also be an option as they go obsolete (e.g., coal in the later years, buggy whip factories that turn into automobile plants, etc.).
Then you have to figure out new ways to serve them. That always kept me involved in Locomotion. TrainFever feels very monotonous because it’s basically the same few industries scattered over the same basic map. Nothing changes and the industrial development is so slow it gets boring. I often don’t go back and play since it’s always the same repetitive play.
I’d like to see my industries and transportation network grow and change so I can’t wait to go back and keep the process moving forward.