On the Ubuntu Forums, I answer a lot of questions about which AMD GPUs are supported by AMDGPU and AMDGPU-PRO. I’ll list here what I know right now.
AMD Radeon™ GPUs supported by the AMDGPU-PRO driver for Linux, according to AMD's website on 04 NOV, 2016.
R9 Fury X
Until several weeks ago, I advised people that AMDGPU would support GCN 1.2 and later GPUs, with support coming for GCN 1.0 and 1.1. In this list there are several GCN 1.1 GPUs (the R9 290X, for instance) so it looks like the backporting to earlier GCN versions is happening. But I don't know how well it is working with GCN 1.1 GPUs. I no longer have one to test. That being the case, I also can't say if Ubuntu 16.10 will detect a AMDGPU capable GCN 1.1 GPU in at install time and set it up for you. I'm pretty sure 16.04 won't for GCN 1.1, but might in later point releases.
For GPUs prior to the introduction of GCN (I think that means HD 7000 and earlier) the open source Radeon driver will be the only option.
Something that may be of interest to users of 16.04: Although AMDGPU-PRO works fine when I boot 16.10, when I boot 16.04 one of my four monitors receives no output. 16.04 with AMDGPU is fine -- all four monitors receive output. Just something to consider.
Legal Disclaimer: I am not an Ubuntu apologist, but I do use Ubuntu and Kubuntu. I am not a Fedora apologist, but I do use Fedora. I am not a Windows apologist, but I do use Windows. I'm not a FOSS apologist, but I use FOSS tools when I can and when they fit the job at hand. I don't find any sense in a religious affiliation with tools and operating systems. That's just asinine.