I (we) think the idea is great, but also it is a lot of work! And I mean not for us, but for the community. The guys over a trainfever.net are currently finishing work on the “Nordic DLC” which will be officially supported by Train Fever. From what I know it took months or even close to a year to do that.
I also know about a UK and a Russian themed project. So let´s see what the future brings!