The biggest thing that enabled me to write that article is that on the Intel family of chipsets, even though some of the implementation details have changed over the years, the fundamentals of the OOO core have been unchanged since 1995.
That is not true for ARM cores. Even if you look within a single family, the individual chips all rather different from each other. The companies with architectural licenses (Intel, Marvell, Qualcomm, Broadcomm) are free to create radically different chips as long as they satisfy the instruction set. To cover the major players would mean to include the popular third-party families like XScale and Tegra, making the landscape much more complex. Coprocessor support for VFP and Java/Jazelle can make things even more interesting.
I'm sure there are many ways to make a great article about the various ARM chip families used in mobile devices. The trick will be in finding a balance between chip-specific information and generally useful information. Something that may be useful for the core ARM11 found on older iPhones may not equate well to a Snapdragon's Cortex-A8 or the Tegra's Cortex-A15 found on other popular phones. Keeping that balance may be a bit of a challenge.