Looks like people don't realize what Iris Pro is.
Iris and Iris Pro is basically the same GPU. Iris Pro only have eDRAM. Both GPU's have the same amount of cores, same clocks. The difference is high bandwith(arguably...) memory on the GPU die.
What's for Broadwell.
eDRAM will be available in most GPU's, if not in whole lineup. Broadwell GPU's will get 8 cores more - 48 core amount.
Few tinkers around GPU's and we end up with 40% faster GPU than Iris Pro, that is available for whole Intel Processor lineup.
But there is one surprise. Some say(

), that there will be a 28W version of Quad Core processor with this GPU. 2.0 - 2.2 GHz CPU speeds. I highly doubt there will be that type of Processor in Intel lineup with Broadwell, but Skylake - everything points that it will be true.
So in the end. If HD5800 will be available for whole Intel lineup, and will be significantly slower than Maxwell cards, which it will be in every way. Not putting at least GT860M, looking at the competition - it will be just laughing at customers faces.
But for that, its still few months from now.