It looks like NVIDIA will not be waiting for the 20 nm fab process for its next big GPU. Riding on the success of the GM204 silicon, the next enthusiast-segment GM200 silicon will be based on the 28 nm silicon fab process. NVIDIA’s GeForce GTX Titan II could be based off this silicon.
Given that this chip will be based on the existing 28 nm process this is going to be a big GPU, over 600 mm²! Since this GPU will be based on the Maxwell architecture thermal loads should not be that bad, but given its going to be a big chip we will just have to see. We could see the GM200-based GeForce GTX Titan II launch is the first half of 2015.