I'd like to get rid of quest markers and have the mission briefings and navigating the city be clear enough that they aren't needed; even if some detective work might be required. Also... the glowing weakspots on bosses, are just lame. Thinking about it, the whole idea of bossfights is lame.
But on the other side of things, I would like to see a lot of in-fiction overlays that relate to gameplay and systems.
If I remember correctly the ability to toggle HUD elements was already confirmed, as well as eye impmants etc. giving additional information about your surroundings. (The subdermal grip they installed in the demo added info about how many bullets you got left in your magazin, by connecting with your gun, if I'm not mistaken)