If you install a valid registered copy of the OS on the hardware, I imagine none. For the people that obtain the OS through not so legal means, then I imagine they'll still be able to get around it as most application on the appstore are obtainable through other means.
technically none of the copies of Mac OS X running on Hackintoshes are "valid" -- Apple's Leopard/Snow Leopard boxes are technically upgrades only, not full installs, even though they work perfectly fine as full installs.
I hope your right, but on most small releases 'tinkering' needs to be done to make it work. We will have to wait and see.