2012 - a lot of new Nikon DSLRs released, 2013....

Both the D1x and D2x(s) had a product life of 3.5 years. The D3x is now 4 years old, its replacement is actually overdue. Also, both the D2x and the D3x have been announced about 1 year after their fast, low resolution siblings D2h and D3. The D4 was announced on January 2012, so the announcement of the D4x can be expected in January or February 2013.