It is indeed speculation on the writer's part, as he points out in the article. What has been covered by other media before is that the BCLK overclocking controls will come back in the shape of BCLK ratios as we have on the Sandy Bridge-E platform (and which was actually supposed to be in Ivy Bridge too). Overclocking is not coming back to cheaper parts, though. Intel has full control over what parts power users and enthusiasts need to buy to overclock (K/X-sku) and they will not give up that control. Most likely, the BCLK control might be disabled in the lower-end SKUs just like they are disabled in the Xeon 8-core LGA2011 parts.
I can’t remember a CPU launch being more highly anticipated than Intel’s upcoming Haswell, expected to be released this year. Much has been said about the microarchitecture - if you want to learn more about it, I would highly recommend reading this article at Real World Tech. In it, you will learn everything that has been made public of Haswell, including details on the scheduling engine, instruction set configuration, memory hierarchy, and more, all in great detail.
Intel immediately discovered a design flaw in tying the L3 and CPU speeds together – if the GPU ever needed to access the L3 cache, the CPU speed would have to wake up as well. With Intel’s focus on power efficiency, this was a huge deal, which is why they will actually go back to individual clock speeds for the Uncore and CPU Core with Haswell.
This is pure speculation on my part, but it looks like the days of overclocking a locked CPU may be upon us again. By being able to manipulate the Uncore frequency separately from the CPU (and GPU) frequencies, there is a good chance that the lower end Haswell chips will become viable overclocking targets for enthusiasts once again. We may never see another 300a, but if we can have a $100 Haswell CPU running at similar frequencies to the $300 part, it will renew interest in overclocking for a lot of people.