I think OpenCL will stay - it has most of its applications outside games / graphics. Or are there any games using it?
Personally i liked OpenCL a lot more than GLSL for compute. Easier to use, more solid programming - less 'just a shader', and it was always faster on any hardware i've tested.
SPIR-V already draws a line between OpenCL and Vulkan-Compute:
"Execution models include Vertex, GLCompute, etc. (one for each graphical stage), as well as Kernel for OpenCL kernels."
I don't know if there are technical or business reasons behind that.
Because there are no plans for OpenCL <-> Vulkan data sharing, we have no choice anyways.
But those extensions are exactly what i want and there should be no big reason to look back to OpenCL.