Taken from Nvidia forum:
"Here is my conversation with Nvidia:
Karthik: Hi, my name is Karthik. How may I help you?
Ed Mario: It appears that all 4K televisions are/will support HDMI 2.0. When will your video cards support this. Will existing cards support 2.0 with a firmware update?
Karthik: Hello Ed,
Karthik: This will be a hardware feature & the HDMI 2.0 will not be updated via firmware.
Ed Mario: Thank you, so what will be the first hardware, and when will it be available? I heed to build a new computer and with the 4K monitors coming will wait for this feature.
Karthik: There is no confirmed details on the model number for now as it is still under testing, so officially I cannot comment on this yet but the future cards will support this."