RX 480 GPUs support HDMI 2.0b so yes it should be possible with one of those. I do not use Linux myself though so can't comment further.
Your TV is the D40U-D1 as the D40-D1 is only 1080p and only HDMI port 5 supports UHD on the TV at 60Hz.
You're right; typo on my part in regard to the TV's model number The RX 480 is in fact the GPU I'm interested in. Hoping the Linux drivers are working at 4K 60 Hz over HDMI :/
I have the same tv and RX 460 does not work 4k@60Hz.
I tired the amdgpu-pro drivers or the ubuntu drivers (both 16.04 as well as 16.10), none would go past 30Hz. I also tried some DisplayPort to HDMI 2.0 adapter which claimed 4k@60Hz - also no luck.
So no 4k@60 on Ubuntu at all on the Vizio D40U at least for now.