Nikon have just announced the replacement for the D600. Equipped with the same 24MP sensor, the main improvements on the D610 are a slightly faster frame rate (6fps vs 5.5fps) and a quiet mode in continuous that shoots at 3fps.
24.3MP FX-format (full-frame) CMOS sensor
Quiet Release burst mode
6fps continuous shooting
EXPEED 3 image processing engine
3.2-inch, 921k LCD display
Twin SD card slots
Wi-Fi connectivity with optional WU-1b Mobile Adapter
Find out more on Nikon’s website.