Writing AI for CiM would be a horrendous task. We can just look at a map and roughly figure out where people might want to travel. But it's very hard to write down how we do it in a way a computer can blindly replicate. If people can't make decent AI for openTTD (which has a much less cluttered map than CiM - if it's the right thing to build a line from A to B, it's easier done in openTTD where there are less obstacles in the way) I don't expect it can be done for CiM.
To quote myself in another thread, though, it is possible to have multiplayer in today's CiM - to swap save-games. Each player plays for five years, then passes the save-game to the next player on the list, who takes over the previous player's transport empire, mocks the mistakes he made, and tries to improve it. It would be organised per-game on a forum thread. Like (warning: bad language) the legendary
Boatmurdered, which was a Dwarf Fortress game played by people on the Something Awful forums.
