Well, it looks like the campaign will be fully playable in a couple weeks! After that, it's polish, polish, and some more polish for a few (at least 3) months. With this in mind, I think we're looking at September.
As today only the hafling sidequest (Gullykin's surrounding) are missing. (around 5 exteriors area, including a little village, a dunjon, and less than 10 interiors area for the village) All the rest has its area done and scripted. So all chapters, and the extension (TOSC) are functionnal.