Emil's proposed schedule includes the feature freeze and first release candidate on 14 April. Following that would be weekly release candidates until Mesa 17.1.0 is ready to ship. Emil is anticipating that Mesa 17.1 should be able to ship around 5 May.
If the branching happens as anticipated, Mesa 17.1 will have about five more weeks for new features. Velikov also followed-up with the likelihood of seeing OpenGL threaded dispatch, anymore OpenGL shader cache features, possibly OpenGL 4.0 for Ivy Bridge and Bay Trail, and other work outstanding in patch form.
Mesa 17.1 has already queued up many OpenGL/Vulkan features since its development began in February. There will be a usual Phoronix feature overview of Mesa 17.1 as its feature freeze comes about plus plenty more OpenGL/Vulkan Linux graphics benchmarks.
The tentative Mesa 17.1 schedule can be found via the mesa-announce list.