The new Nikon D750 will be for action photography and feature 24.3MP FX-Format CMOS Sensor, Multi-CAM 3500FX 51-Point AF Sensor (same as of Nikon D810 or D4s camera), EXPEED 4 Image Processor, articulating LCD screen and built-in Wi-Fi support.
If the image below is real we can say it looks like a Nikon D600 with a tilting LCD screen. See more rumored specs list of D750 here.
According to the source the image below is fake!
First Image of The Upcoming Nikon D750 Camera Leaked