Shorter dev cycles and an emphasis on making things easy for devs, i.e. Sony, MS, Nintendo sticking with the PPC core architectures and upgrading components. A continued emphasis from Sony on PS3(4)/Vita integration. Consoles to start out slim and quiet, and then get even slimmer and quieter not the fucking jet engines this gen started out with. Emphasis on the quiet, seriously hate how loud consoles are. 360 is good with game installs now, though if MS go BD next gen they'll need decent drives that aren't loud as fuck or imma be pissed. More modern, competitive multifunction operating systems if 360 has Metro UI stuff and a great media player with better codec support a browser that maintains parity with the functionality of IE on PC and media server features count me in, same goes for PS4. Control systems to be determined at launch and bundled with every system, no new systems half way through. Keep it simple and locked down. App store for stuff that isn't just games so I can actually use my console as a media center and use apps like Boxee etc on my console without hacking it.
Basically improve on what they've been doing already. This gen was/is fuckin great