The head of GSC Game World, Sergey Grigorovich has confirmed in an interview that S.T.A.L.K.E.R 2 will require an always-on internet connection for anti-piracy measures, it will stream "text information, code and quests" through the data stream. It's a weird thing to have for S.T.A.L.K.E.R 2, because then Grigorovich says in the same interview:
Protection from piracy? Part of the content will be located on the server and downloaded as the game progresses. Permanent internet access is required. Text information, code and quests will be loaded through that connection. Software piracy is an issue for us, we try to fight it, but within reason.
If people can not afford a licensed version, it is to our advantage if they download a pirated copy, and then want to buy a license. In Ukraine, there are different products that people love so much that they buy a license in principle. We want to create just such a product.