right now we cannot really say. The version of the game out now is PvP only and online multiplayer only.
If the SP campaign allows you to play offline or you can run the game offline with no internet, then chances improve.
According to reports, there's going to be offline bots for multiplayer, wouldn't be too far off to have offline singleplayer. We'll know soon enough.
I was hearing that it requires persistent internet to work even for the Campaign as it is tied to Battlenet. The only 'Offline' campaign available at this stage I know is accessible through Xbox and PS4 only.
Has anyone actually got the campaign to work while offline from Battlenet?