Just for parents? Why not just give all users the ability to block certain usage patterns and access to applications -- kinda like the StayFocusd plugin for Chrome. Hell, charge a monthly fee to access the web interface to manage it; you get a mechanism to induce friction and you get a subscription business -- I would pay for this shit since I value my attention more than someone who you pick off the street. How does 300$ a year sound? like weight watchers for attention (we know that model works already). You get a nice upsell on an already expensive device. Maybe this will be a nice way to maintain profits given that people aren't replacing their devices as often anymore, keep trying the stunt of billing incremental features as revolutionary and people will stop believing you.