Existing EKWB and XSPC blocks will already get the CPU/GPU temps so low that any overclocker will hit voltage max long before temps become an issue. On water, my 4670k idles at mid-to-high 20's and on heavy load p95 settles in at low 60's. Glad to see progress being made here. But I'm wondering how necessary it is. Rather, I'd like to see them working to bring the cost of custom w/c down so that more people can get into it.
I would say they could easily lower the cost of CPU blocks but the GPU market requires a hefty engineering team. The price of GPU blocks remains high because of GPUs coming out quickly and many different models and revisions from vendors requiring different block mounts. They pretty much can charge so much because its a premium and because they can get away with it. (plus they're small companies anyway and there are very little number of people doing custom loops)
On the bright side CLC manufacturers are making some strides for people who are interested in custom loops but don't have the cash for it. For example, some of Cooler Master's Seidon pumps allow you to start off with a closed loop and then later open it up for a custom loop. Also somewhat notable is that NZXT's Kraken CLC's are becoming popular in regards to mounting them onto GPUs.