It seems that Nikon is finally ending the fiasco they had with the D600 once and for all. As you may recall, the D600 suffered a terminal illness which caused dust (or oil) spots to accumulate on its sensor. At first Nikon denied, than offered a free repair, and finally they were ordered to stop selling the camera altogether and brought on the D610 which solved the issue.
If you spent $1,800 on this camera this must have been a frustrating 2 years for you. Now Nikon is ending this marketing disaster once and for all and doing it quite well (although pretty late).
Procedure is not hard, but it seems limited to the persons who were in the initial lawsuit:
As a result of your involvement in the Nikon D600 camera lawsuit, Nikon has offered to immediately provide you with a new D610 camera in exchange for settling your individual claim.
In order to accept this settlement offer and receive a D610 you must complete the following steps:
1. Complete and sign the attached Qualifying Statement, Short Form Release, and Confidentiality Agreement.
2. Register your D600 camera at the following link: https://support.nikonusa.com/ci/documents/detail/5/144/12/33a9814ba32973bc88a6c149468e888c2cd1adf5
3. After registering your D600 camera, you will be prompted to create and print a pre-paid UPS Return Label and packing slip.
4. Pack your defective D600 camera, packing slip, and the original signed copy of your Qualifying Statement, Short Form Release, and Confidentiality Agreement in a box, and affix the UPS Return Label. Drop the box off at any UPS facility. (Visit https://www.ups.com/dropoff for hours and locations.) You may also arrange to have your shipment collected by a UPS driver.
5. Once Nikon receives your D600 and the required documents they will mail you a replacement D610 camera.
My thoughts are that Nikon could have saved themselves a lot of hassle if they addressed the issue like this right away.