There seems to be an increasing emphasis on the 3D visual-tactile element of the game, including miniatures and dungeon tiles. I would not be surprised if we see pre-painted plastic terrain features at some point. Frankly, I have no problem with Wizards producing this kind of stuff -- it probably draws lots of new, especially younger, people into the game. Kids (of all ages) like toys. I know that when I was 10 or 11 I was fascinated by the elaborate Warhammer setups they had at the LGS. Miniatures-scale battlemaps will probably be included in every module.
Because the rules have become more complex, there seems to be a movement in the direction of making D&D products easier to use. The tactical element of the game is popular but challenging, and so certain modules now include round-by-round tactical advice for the DM. Books like Complete Warrior and PHII include character-optimization tips. This kind of thing is also good, in my view -- if we're going to have a complex ruleset, WotC had darn well better reach out to new players and make the game easier to learn (and especially run). I and many other players have complained about the game being too rules-oriented, but really my complaint isn't about the level of complexity, it's about the difficulty of DMing (and especially tweaking the assumptions of the game, like magic level or power level) given that complex ruleset. If WotC could find some way to remedy that situation (i.e. make the game flexible but easier to run) then I would be very happy.
As for the actual rules of the game, hopefully the designers will find a way to streamline them without dumbing anything down. The game should be easy to learn and take a lifetime to master, which means that the ruleset needs to be intuitive, elegant, and efficient and yet still provide infinite options for both players and DMs to customize the game. That's a tall order.
I wouldn't be surprised if 4E is balanced per-encounter rather than per day. I certainly wouldn't mind if that was the case. When it comes to D&D there are certain cows that I do hold sacred: the six ability scores, classes and levels, etc, -- but not per-day balance.
Also I would be remiss if I didn't suggest that WotC hire some talented writers (not game designers, writers) to pen some really exciting flavor text for their books. That would go a long way toward making me a happier customer.