Suicide Squad will require an online connection even in single player mode

According to the Suicide Squad FAQ, the game will always require an internet connection, even if you are playing the single player mode:

Yes, an internet connection is required to play Suicide Squad: Kill the Justice League solo or via online co-op.

The exact reasons for the need for a constant connection to the network are not known, but there are rumours that it has something to do with the co-op mode of the game. This also means that if the developers disconnect the game's servers in the future, players will lose the ability to play the game even on physical media.

Most game developers use a one-time DRM checking system, which is much more convenient, as the Internet connection is required only once, and then users can play games offline.

Source: videogameschronicle