These 17 Patches Effectively Put Intel Mesa Done With OpenGL 4.4 & 4.5
If you head over to the convenient Mesa Matrix, you will see ARB_enhanced_layouts is the last "red" extension for the Intel i965 DRI driver... After that, she'll be at OpenGL 4.5.
The patches done by Arceri at Collabora implement this OpenGL extension for "Gen6" Sandy Bridge and newer while the current OpenGL 4.x support with full compliance is currently just for Intel Broadwell and newer.
These patches have yet to hit Mesa Git and for now are floating on the Mesa-dev. The patches conclude with marking the Intel driver done with ARB_enhanced_layouts.
Past OpenGL 4.5 there is still those "2015 ARB Extensions" plus it's widely believed Khronos could be releasing a new OpenGL specification later this month at SIGGRAPH, thus the catch-up game is not yet over.