As the graphics engines become more sophisticated and more powerful, I think the next step will be (or IMO should be) making the crowd and sidelines more realistic. While the gameplay is obviously priority #1, the typical sprite based animations for the crowd are terrible, and there are rarely more than 15 or 20 people modeled on the sidelines. What I really want to see is a full bench of 45 players (or even 80 for NCAA), a coaching staff, medical trainers, media ...
10 years from now, I think that the video games will be mostly indestinguishable from the real thing, at least they should be. Taking Moore's law to its conclusion, microprocessors will reach the limit of their capacity by 2018 or shortly thereafter. At that point, it's physically impossible to make a transistor any smaller, and that's spotting a company like Intel two full generations of products beyond what they could conceivably make now -- giving them the benefit of the doubt that they'll make a functional chip from sub-atomic transistors.
The need for speed in processors will probably wane over the next 5 - 10 years as the push becomes more efficient code on longer life, lower power, zero heat emitting hardware. At some point, it becomes pointless to make the machines any more powerful when it's become virtually impossible to reliably and affordably cool the CPU, meanwhile the capacitors on the PCB are exploding like 20-year old batteries after 12-months of service life.
EDIT: Regarding the next thing in online games ... it would not be difficult to expand a game such as Madden to allow 22 on-line players, but rather the communication and coordination of 11-on-11 would require some thought. My bet is that The Next Big Thing (tm) is real-time advertising on-line. You start up Madden 2009, and while it's loading in the background, your PS 4 airs a Coca-Cola commercial. The in-game "billboards" change routinely, advertising products you buy since your PS 4/DVR/Media Center has a record of everything you regularly buy on eBay, Amazon, or search for in Google.
What do you think a thousand tiny little swooshes on modeled jerseys and 4 mid-qaurter commercials is worth to Nike? Or EA?