It looks now that Mesa 12.0.0 3D Graphics Library Release Candidate 2 is coming this Friday, on June 3, the RC3 build should be released one week later, on June 10, and the final version might hit the streets on June 17, 2016. As noted above by Mr. Velikov, if things go smoothly, we should get Mesa 3D 12.0.0 final on June 10.