EDIT: That would be suicide (for the whatever 5% of their sales the mac brings in!). If they imposed a rule like that AND continued to neglect the app store the way they do, droves of developers would leave.
Unless they rethink or overhaul their sandboxing system to allow a bigger class of applications (essentially, most of what's out there), they won't be able to move power users to the App Store.
Unless they rethink or overhaul their sandboxing system to allow a bigger class of applications (essentially, most of what's out there), they won't be able to move power users to the App Store.