EU has already started an antitrust investigation into apples app store. Most likely they will get hit with a huge fine.
> The European Commission has opened formal antitrust investigations to assess whether Apple's rules for app developers on the distribution of apps via the App Store violate EU competition rules. The investigations concern in particular the mandatory use of Apple's own proprietary in-app purchase system and restrictions on the ability of developers to inform iPhone and iPad users of alternative cheaper purchasing possibilities outside of apps.
What might lead one to think it hasn't already attracted the interest of regulators outside the US? These battles are fought globally.