A recent relevant example; PS3 entirely removed Linux support a couple years in, even though they were bragging about it quite a lot at launch. Technically, you could keep it, you just can't visit the PS Shop or use any online features (which you paid for, as part of the price of the console) ever again, that's all. Not sure if disc-enforced updates apply to this one or not.
Since early adopters are more savvy, Sony has every reason to tout their lack of DRM compared to the Bone, for now. Will their DRM be better throughout the generation? Unless Sony makes a pledge (and really, even if they do), it's their choice, not ours.