I imagined trains in VS similar to minecraft but modular and all the modules would be similar in size to the minecraft's minecart. So you have the engine cart together with the coal cart and then you can add your carts to transport ressources or people. Later they can simulate the weight and the tractive force of the train. And for example if you need to go up the mountain with many carts you would add a second engine. There's a mod(wip) similar to this idea: Rust and Railroads.
Also, remember that our Seraph would be building those trains on his own with primitive technology. So the model of the engine and the cart would be rough and simple, it won't be a shiny factory new locomotive.
But I don't think that VS team will add trains into the game in the near future. They first need to create a reason to transport a lot of ressources over vast distances(sparcely generated villages would be one). Certainly first they will add horses, carriages and boats with hopefully generated rivers.
