Things we won't see:
User generated content, platform publishers can't charge for it.
Tradational MMOs. They take too much of a players time. Platform holders don't want you playing one game for so long, they want you buying new ones. thats why we have map packs for omp fps games now. Maybe some players do play for 300+ hours, but they are buying things as they go. Freemium MMO could work. That is the way DCUO works on PS3. But it works because Sony owns it. No way MS will allow a 3rd party, say blizzard, to put something like WoW on a xbox. Sony could bring the next EQ out to PS4 tho. But I don't think it would follow a pay to play model, would instead be more of the freemium type.
Second hand games.
New IPs. Not going to happen for awhile. As dev costs go up risks taken decrease. Untested IPs will be taboo, from the big boys.
Free online. I think MS and Sony both have multi teired/priced online packages they will be selling. MS showed how viable charging for Live is, and Sony missed a ton of cash by not having a similer system in place.
Things we will see?
Prettier graphics, smoother framerates. I doubt think they will be revolutionary, but they will be nicer. Hoping 1080p at 60fps. But seing as how the number one HD TV sold in stores is only 720p, I doubt devs/pubs will be too fussed. 720 is still the sweat spot for living room entertainment.
More digital downloads.
Better online performance from everyone, including Nintendo.
A VERY large kinect 2 push. Built in, and fully featured. Browse with it, talk to it, use it. Its what MS wants. Expect a flood of games for it from big name pubs too. I believe MS will try even harder to capture what they believe as the Nintendo crowd. So get excited for Kinect 2.
Expensive hardware, controlers, and memory storage. And Games. I expect AAA games to retail for 80usd, while still pushing dlc. Perhaps in the form of year long annual passes. 80 for the game, 40 for a years worth of dlc.
Fewer game releases. This things are going to be pricy and take longer to make. So I think it is possible we will see less AAA releases. Stuff like PSN and XBLA releases could become more front and center and less side show. They will be cheaper, easier, and faster to make.
And like everyone else, I think, sequels sequels sequels and more sequels. Call of Battlefield 13 incoming. All of the big names you can think of now, get rebooted and continued on the next gen hardware.
I really don't see any revolutionary things happening next gen. Really, there weren't anything this gen. If you played on a Xbox One last gen, you saw little difference this gen. You played online, you could buy arcade games, you had DLC(last gen w/xbox one). This gen brought stuff like movies/tv shows/netflix/facebook/twitter/wireless controlers. I expect next gen to build off of that.
MS would like to offer you IPTV(maybe replace cable/sattelite), they want to brodeen their partenerships to sell you more things. They want to become the one box under your TV. That is their aim. It is plan as day.
Sony would like to be just like MS.
Nintendo is going to do what Nintendo always does. Their focus is on games. Finding new ways to present/play those games(analog stick/motion controler/tablet controler). Their online should be better and cover far more games. But they aren't aiming to replace your PC/tablet/cable box. they are aiming to sell you games. So from them expect more of the same, you know what your getting.
Games are seven things in on MSs new dash on xbox360, so you can get an idea of where games fit into their thinking going forward.