I'm pretty sure if Darvish retires he doesn't get paid - so doubtful he would just randomly retire and insurance won't pay for s*** unless he's actually injured. That said, SD is clearly in a must win now mode. They probably only have a 2-3 year window (and I kind of hope this blows up in their face as I don't like this approach in general). The lower luxury tax hit obviously helps a little bit right now, which is why they did 6 years, but it also tightens their window even more as paying Darvish $20M per year for 3-4 years at the end of the deal, when he's unlikely to be playing (effectively) is going to further hurt their financial flexibility.