The new Ultra HD Blu-ray format has two different protection levels. One is called AACS 2.0 Basic, where the title key is included with the disc. The second is called AACS 2.0 Enhanced, where you will need an internet connection at least one time to have the key delivered to your player.
Once the key is delivered for an enhanced disc, you don't need the internet connection again for that particular disc and player combination. If you want to play it in a different player, then you'd need the internet connection once more.
I suspect the vast majority of the discs will be the enhanced variety.
Of course, this applies to the UHD Blu-ray, not the normal, 1080p Blu-ray discs.