I second the
“6. AI companies. How about some competition from other companies? Of course an optional setting in the difficulty settings.” idea. In fact, from what I’ve read (haven’t tried the game yet) I would personally love it if the Business side of the game was expanded to work closer to how Railroad Tycoon II & III did, with stock trading, issuing bonds, taking over AI companies, it made you feel like you were indeed the CEO (and maybe owner) of a railroad company. Which is something most newer railroad games lack.