Update: the D4s development is now officially announced.
Digicame-info reports that Nikon may announce the development of the D4 successor next week during the 2014 CES show in Las Vegas (in addition to the two lenses and D3300). The official announcement will be in February and shipment will start in March - this is pretty much in line with what I have been reporting for the past few weeks. Nikon must have some kind of an official announcement before the Olympics, since many photographers will probably be using the new camera at the games.
For now the information I have been receiving points to a new D4 model with:
- the same 16MP sensor
- higher fps rate
- improved AF
- better low light performance
- improved video