Even here, if they reaaaaalllly cared (and had good reasons to, other than "we want to lock in customers"), they probably could take the feature away - they'd j

Even here, if they reaaaaalllly cared (and had good reasons to, other than "we want to lock in customers"), they probably could take the feature away - they'd just need to play the CYA game much better, and be willing to risk a hefty fine based on whether a court believes your reasons for technical infeasibility. After all, not everything that was technically feasible stays so in a changing environment. Another think they can do is just try occasionally, and see if people give up.