On 13 August is when the Khronos Group will be announced the next-generation OpenGL at SIGGRAPH in Vancouver. Given that it's going to be going head-to-head with DirectX 12, AMD's Mantle API, and to some extent Apple's Metal, we (and others) assume this is most likely where they're going to make the jump to OpenGL 5.0 rather than OpenGL 4.5 for the next-gen functionality.
It's widely anticipated this next OpenGL update will focus on best practices and interfaces for lowering the overhead of drivers as has been the big theme with the Direct3D, Mantle, and Metal releases. There's also plenty of other possible features to OpenGL 5.0 expressed by developers ranging from a cleaner object API to an official GLSL bytecode for shaders to improvements in direct state access to a better GL utility library.
On Wednesday the Khronos Group will have a session about OpenVX and OpenKCam followed by COLLADA and gITF, then a WebCL session, a mid-afternoon session about OpenCL with SPIR and SYCL, a WebGL update, and then ending out the day before parties is the much anticipated OpenGL / OpenGL ES talk. The GL/GLES talk is described as, "OpenGL, OpenGL ES and the 3D API Landscape - Hear how OpenGL ES and OpenGL are evolving to meet the needs of next-generation 3D applications, providing lower overhead and greater graphics richness on mobile and desktop platforms." Learn more at Khronos.org.
This weekend the Khronos Group also put out this brief teaser video ahead of SIGGRAPH 2014.