Look at it this way . . . sure, HD4600 and below will probably never see utilization. But from Broadwell on up, those iGPUs should be quite useful for anyone that cares to program for them (OpenCL 2.0, Vulkan, DX12). The hardware is ubiquitous and will continue to be ubiquitous. Developers would be crazy not to target that hardware, since it will give them a leg up over competition that doesn't.
Unlike AVX2, all those features are/will be available from the lowest-end Broadwell up to the highest-end Skylake and beyond (Gen9 may add some stuff but whatever, point is Gen8 is OpenCL 2.0 compliant).
But yeah, on Haswell, I don't think we can expect much to be done with the iGPU outside of simple display duties or some awkward OpenCL 1.x functionality.