As much as I’d like- and hope to see day-/night cycle myself, the teaser was not to ask for that. It was simply for texturing and having fun experimenting with rendering.
When people are wishing for day-/night cycle, I hope you take into consideration that it would probably demand a lot from Urban Games, as well as making modding a heavier process, depending on the lighting method chosen. Even though it would be very awesome to see day-/night cycles with lit train sets, Urban Games most definitely knows what is better to put effort in.