There are interesting links to read That should be pretty nice to see GalliumNine being pushed in Wine-Staging. In a nutshell once you read links above you may understand that it requires a lot of work :)
  • rewritte the code
The second part written below is my own opinion so could be really useless to read

I used one of my PC for Mesa/GalliumNine. This is a dedicated PC only for this project. To be honest this is really cool when you notice that you can play your favorite games using Open Source Driver and AMD Card -- I am speaking for AMD users here --. It does not mean that it works all time and it does not mean that you may have interesting FPS for all games.

For the 4 past years I tested a lot of games (Windows) using wine and my GTX 680 -- NVIDIA Card hard-moded to GRID K2 --. I used my own AMD cards for perhaps one or two months to play only a couple of games. To be more precisedI did this because I worked on Xen VGA PassThrough -- to be able to access my own AMD graphic card for my virtual machine --. I discovered GalliumNine in October, 2014.

Gallium Nine is really interesting! This is from my own point of vue. Wine developers shared another point of view. Quite understandable!