I don't think they'd sneak it in, as people would sell the systems and they'd be back at square one as publishers wouldn't be able to sell games. The Xbox one would dissapear as fast as the old Xbox hd drive. Sony were bad for updates, they inserted software limiting use of non licensed DVDs.
Sony are being sneaky though, as they are releasing a type of kinect system like the Xbox. They're selling it separately, but from what I've seen it may play a big part of the ps4.
The thing is.. Once you purchase this it makes it more expensive the the Xbox one which has a kinect built in. It's a good sneaky sales tactic.