Nikon's intention is to do absolutely nothing for current D600 owners. It's been hashed before. D600 owners can keep them, sell them on their own or look for a kind-hearted store owner. Nikon has extended a large middle-digit in the form of the D610 and left us all hanging. Best you can do is argue with them to have them once again swap out your shutter if you're experiencing issues.
Personally, I have no desire to trade mine in now that it's working cleanly - it's a great camera. But it's a taste in my mouth that I'll remember when I'm ready for a new camera down the road.