Honestly? I would say the best possible thing would be graphics that are as real as they can get to be equal to real life. Better yet, the ability to literally be the main character of the game. Kind of like in the movie Gamebox 1.0 or something resembling the combat training rooms in Ender's Game where they had the suits that disabled their limb(s) that got "shot." Basically you use your real person to interact in-game with everything and so on. But something like that is not possible in the short-term future, it seems.
So in today's world with today's technology, the graphics need to take hints from what they were a few years ago to improve now. As an example, in Reach, Homefront (and with this I disregard every horrible aspect of the game, and only use it as support for what follows), L.A. Noire, and probably many more recent games, the problem is the interactable models just plain stand out and glow. Its like the old school cartoons/animations where the only objects that would change position on-screen would be a more vivid color than the objects that were left untouched. It's just as enhanced visuals of the game world are developed problems like that can arise. Relating to my statement at the beginning of this paragraph (and I'm probably contradicting myself from earlier here), games used to have graphics where things like dropped guns fell into the environment and looked like they belong there, but now when a weapon is dropped and hits the ground it just appears straight out of place.
Finally, the fact is, as graphics improve to be better and better, whatever there are problems with now will just look even worse and stick out even more. It's like washing a dirty car then leaving a circle in the center unclean. Like improve the detail of a forest to be hyper-realistic, then omit the properties of that scenic pond in the foreground (the complex stuff like surface tension, mixing with debris at the shoreline, and actual wetness of whatever the water touches, or even the fact that water splashes); you will have major problems there and a true eyesore. There are many things that could be improved now before we move on to real-life graphics in videogames, and if said details are imminent, I am much happier returning to my 2007-era (or around that timeframe) games and their graphics, for the simple reason that though they aren't better than today and they aren't as hideous as those before their time, everything is balanced at the same stage of ugly so that it all fits nicely.
But that's just my ambiguous, multi-directional opinion.