First, the device still has the same memory slots, WiFi card slot, mSATA SSD slot and form factor. That's about all that has remained the same. The third generation of NUCs will get a CPU upgrade as well. There will be two versions: one with a Core i3-4010U CPU, and another with a more powerful Core i5-4250U. Both of the units have new Haswell chips and will thus be able to run a lot more efficiently. The Core i3-4010U CPU will carry an HD Graphics 4400 part; the Core i5-4250U will carry a more powerful HD Graphics 5000 part.
On the inside, the device now has an added normal SATA port, as well as SATA power. This means that it will be possible to add a second drive to the device beside an mSATA SSD. Let's hope that a number of manufacturers will come out with enclosures with support for either 2.5" or 3.5" drives. The board also has an internal header for two USB 2.0 ports.
External connectivity has also gotten a welcomed refresh. The USB 2.0 ports have now been replaced by USB 3.0 ports, along with one extra port. Together, this now gives the NUC a total of six USB ports (four USB 3.0 ports and two USB 2.0 ports through the header). Other changes include the removal of both HDMI ports in favor of a mini-DisplayPort as well as a mini-HDMI port. Gigabit Ethernet is still present. Lastly, the new NUC will also feature a front 3.5 mm audio jack for headphones, meaning that it will now be possible to get analog sound out of the device.
Intel indicated that the third generation of NUC devices would be released sometime during Q3 2013 and would be priced in line with the current generation of NUC PCs.