Full offline gaming functionality is still not possible, but it's likely only a matter of time before some enterprising modders figure it out.
However, one thing worth noting is that you cannot save your game locally, right now. According to modder Azzer, he told Rock, Paper, Shotgun that making a UI template and a redirection for local hard-drive saves is entirely possible and not that hard to do.
For now, that's the placeholder fix for people who just want to play offline...a quick-fix from gamers for gamers. Have fun.