Not going to happen in 2012, and might not happen in 2013 either...the current going rate for a D700 is around $1800. The D600 is coming in at $2100. Used D600 bodies will likely go for $1900. This should push the D700 down to $1500 in the near future (within one year).
Eventually, it will hit $1000 though. But it probably won't be until at least mid 2014.