Yeah as said in a previous post, I hope they add an espionage system into the game. I never really liked Civ 4's espionage, but I'm hoping they create a whole new one that is more interesting to me (personal taste, I know).
I absolutely agree. Civ 4 did a lot of things well, but I never felt like espionage was one of them. I'd love to see it back in the game, but with a different mechanic.
Ditto with corporations actually. I liked the idea of them, but the implementation always felt a little rough to me. That was one of the areas where I thought Civ 4's complexity actually worked against it.