They could turn it all on, but i dont think they would. I think you buy a product based on its ability, if they change that stuff then its not the product you bought. So MS will be sued, mostly cos of the internet issues etc. Would be like buying a kettle and 2 months later they say "Nope, no more hot water, only lukewarm water". It totally destroys the reason the product was bought for.
So yeah, they could turn it all on. But people were moaning cos there is DRM. Now they are moaning cos MS may turn the DRM on maybe. Im not saying your fears are not justified, just that people are moaning whatever MS does. Hell, even Sony could add DRM in the future. But know one is on SOnys case on what they may hypothetically do in the future.
Sony touted the PS3s ability to do something or the other with Linux. They later removed it resulting in an uproar. However, they could not be sued due to the EULA stating that Sony could change the features of the device any time they wanted, regardless of what they promised when you bought it. You could agree to the new terms, or not. But you couldn't sue them for changing them. I have no doubt MS will have the same thing in place.
I also don't think the "Sony can change their stance in the future but no one's giving them grief about that possibility" argument is just. A lot of people could do a lot of things, but we don't necessarily condemn them for what they have the potential to do. MS, on the other hand, is being condemned for what they themselves proudly exclaimed they intended to do. They haven't reversed course due to a change of heart, or epiphany that their approach was a misguided one. They changed course because they finally realized how royally they had screwed up. To me it's more like someone hellbent on abusing their spouse, but not going ahead with it not because "you know what, this is wrong," but instead because "you know what? I might end up going to jail." They have every intention of doing it, and may feel it's worth doing in the future, but at the present moment they've decided not to out of fear of reprisal, not out of morality.