Just some time ago, I let myself go and wrote about how upset I was about the (missing) support for my new RX 470 on Linux.
Today AMD released the amdgpu-pro driver 17.30, with support for Kernel 4.10 and Xorg 1.19. So my setup is finally not useless anymore. Details are on the AMD download page.
I've just installed the driver without any problems, after a reboot it works just fine. Videos are playing and I could start Civilization Beyond Earth from Steam under Ubuntu 16.04.3 with HWE.