I don't like the idea of difficulty sliders, although I can see the appeal. I'd prefer to see an improved pointer system, with an improved ass man, also improved scouts would be central to this. The reason I would prefer this to sliders is because I want to learn how to use this game. Not by reading guides, but by playing it, even if it is with in game help.
I'd also like to see a better training academy aspect. You may even be able to start out as a coach there. I know I'll probably never see it, but being in charge of younger teams, with more emphasis on the training aspect, almost a side game, or make it into a tutorial.
Finally, a limited edition version. With a book, and a huge manual, and a big box and limited edition things!!!