I've played this game off and on now for a few years, I usually have to take time away from the game so that I can try to keep it fresh. I don't usually post in forums but I thought I might share some things that I think might make the game a little better.
1. Offer a corporation bank. Members can either contribute voluntarily or the corporation could set up a required donation amount. This money could be used to hire workers or loaned to members to help them build their stations or their fleet of trains, etc.
2. Change the predictability of the game. People have figured which goods are coming up in the next era and they know where they will be located on the maps. Move their locations around even if its just one or two spaces over.
3. Have spaces that can be purchased by corporations, they can build whatever available facility that they want on it. Of course you would probably have to cap the number owned. The corporation could control who uses their facilities and they can also be traded or sold.
4. The biggest thing that I think would change the game play is track dynamics. I am not even sure if this is possible in this game due to amount of programming involved. It would be interesting if the terrain affected times and train degradation. If a train has travel through a mountain this would be much slower and cause more degradation to a train than if it were travelling over the plains. Maybe there are two routes to a facility, one might be more direct and take less time but the other might cause less damage to a train, but that would also involve being able to set up which route a particular train takes.
5. A tweak to the trading element. If I am picking up grain for cattle then that grain should cost me something just as IRL. This also affects supply. If I go to pick up cattle but they haven't been properly supplied with grain then they would cost me a lot more and if they cost me more than what the city pays then I have to move grain to cattle to lower the price. I realize the current system does this but with wait times. Let me try to explain the difference: under the current system if I am hauling cattle and I am away from the game and cattle is not being supplied it just takes my trains longer to make the trip. With my suggestion if I am away from the game and cattle are not being supplied then it will end up costing me more per cow which will affect my total revenue, if I don't have enough money to purchase the cows then I cannot make any revenue, if the receiving city/facility is paying less for the cow then I am paying then I am losing revenue. Therefore it is in my best interest to make sure that the facilities are properly supplied.
6. An alternative for purchase of gold. I have played several games where "gold" can be purchased with in game currency. There will always be people willing to purchase "gold" with real money so that they can reap the benefits, however this puts those who cannot afford gold or who do not wish to purchase at a disadvantage. If I purchase 1000 gold and at some point during the game I need x number of currency to finish a building or buying an engine I can sell some of my gold to the marketplace. This gold can then be sold for in game currency. This would probably encourage more people to buy gold so they can trade it for in game currency.
Anyway these are just some of my thoughts. Maybe some have been considered and maybe some just cannot be done.