Intel has not always charged a premium for overclocking and never stopped BCLK overclocking per say. As you said the big issue was the integration of the PCIe and DMI controllers. The BCLKs clock generator was tied into all of them.
From what I remember, Intel separated the clock generator in SKylake so instead of the 100MHz BCLK being tied to PCIe and DMI, it is its own clock generator making it capable of overclocking with the BCLK again.
I don't think that Intel ever was against overclocking with non K/X series CPUs but rather they sold those as a guarantee that this will overclock due to the unlocked multiplier while overclocking with the BCLK is much more of a shot in the dark due to chip quality. Most i5 2500Ks would hit 4.5GHz with a multiplier bump and a slight increase to the stock voltage. These SKylake CPUs will be much like a GPU now, they will vary depending on the quality of the chip and luck of the draw.
The biggest news mentioned is whether non-Z boards will allow BCLK OCing. Joe and I have already found many H and B boards that allow CPU multiplier adjustment even though Intel doesn't officially support that on anything but a Z board. If you can indeed modify the BCLK on an H170 board, that is HUGE. If they would add unrestrained RAM OCing on an H board, that would be another big change.
The BCLK OCing change here is mostly tied to the CPU, not the mboard. You've already been able to OC locked chips on BCLK, it just hasn't netted you more than a couple hundred MHz. Most the Z97 mboards that run across my review plate have troubles going above 105 MHz ( though one Asus board was able to make 108 MHz, which would hit 4 GHz on a 4170 ). You can take the BCLK higher using the 1.25 and 1.67 ratios, but I don't know if a locked chip can handle the straps. I suppose we could experiment on that.
"If non-K processors can attain clock speeds comparable to the enthusiast K parts, Intel may have undermined the sales of its entire unlocked product series."
I disagree. Non-K processors already outsell the K series by a magnitude and this will not really change things. What can and will change is someone on locked Sandy/Ivy now buying locked (as it's cheaper) skylake (i3, i5 or even i7) and overclock it a bit. That could make all the difference, because locked i5 6400 or even 6500 for example is not worth the change for almost anyone already on sandy i5.
The 1230v3 was also "not supported" on z87 boards for long time, and then people just start to assemble such configs and the official specs got updated. When I built my pc with msi z97 and 1231v3, it was not officially supported by the board. So, I think the v5 version should also be supported.
Yeah, just read same from another resource. Looks like Intel screw things up, damn it! This is what monopoly does, really hope Zen will bring a new breath into the CPU industry. Anyway, the 1231v3 will serve me well for at least another year.