Everything we've seen from Jobe suggests that he's leaving. I'll be gutted but I'm in a place where I can appreciate what he did for us, thank him for his efforts and be a supporter of his career wherever it takes him (and especially if it gets him international recognition).
The family seem to be very detailed and precise in career planning and Dortmund makes perfect sense. Let's not forget that he didn't just sign for us because we're Sunderland. He did it because of Dodds and to a lesser extent Speakman. The family will know most of the key people in Dortmund, they will know how to quickly get the best people around him and settle him in quickly. They'll have also had detailed discussions about every aspect of the plan with the technical staff.
Jobe will be starting Champions League games next year for a huge club who value young players and away from the pressure of the English media. The move couldn't be any better for him really.