NVIDIA's mid-range GK104 served as the flagship of this generation because the chip exceeded performance expectations, giving the company time to perfect the high-end GK110. By the time that NVIDIA's Kepler refresh starts shipping, TSMC's 28nm manufacturing process should be refined enough to mass produce the GK110, a 7.1 billion transistor chip on which the low-volume Tesla K20 GPGPU computing accelerator is currently based. The GK110 will reportedly power the GeForce GTX 780, offering a massive 40-55% performance increase over the GeForce GTX 680. The site heard the GK110 packa massive 2880 CUDA cores and a 384-bit GDDR5 memory interface; Pricing is said to be in the $499 to $599 range. The GTX 770 may also be based on the GK110.
The GK104's replacement will be the GK114, this chip will go into cards like the GeForce GTX 760 Ti and GeForce GTX 760. It's the same chip as the GK104 but with higher clockspeeds, so you can expect sizable performance increases versus the current GeForce GTX 660 and GTX 660 Ti cards.
Just like the GK114, the GK116 is anticipated to be nothing more than a GK106 with higher clockspeeds. The chip gets demoted to the GTX 750 and GTX 750 Ti, so with minimal R&D these cards will also have big performance gains over the current generation.