Intel are not dominant in CPUs. Intel are dominant in desktop/laptop/commodity server CPUs. ARM based architectures have dominated in phones for a long time, and other markets (set top boxes, embedded systems, etc etc) have different dominant architectures and manufacturers.
ARM architectures are not going to be killed off by Intel bringing Atom/Core down the power ladder and neither are Intel going to be killed off by ARM architectures moving up the performance ladder. Nobody here is an underdog they haven't always been.
This comparison is an old Atom vs a brand new Samsung Exynos, neither of which are suitable for anything else other than crappy little netbooks/nettops. Compared to a Celeron/Pentium/Athlon they are slow and compared to a smartphone/tablet SOC they are slurping power, Atom is worse at idle but both are using far too much under load for the tight chassis of a phone or thin tablet. It's an interesting comparison but it doesn't tell us anything for definite except "Samsung's new Exynos better for Chromebooks than old Atom" - which was kind of expected anyway. New CPUs tend to be better than 2 year old ones ... even AMD manage that sometimes. Note that the Bonnell (Atom) architecture is actually 4 years old and is only now being beaten on performance by an ARM architecture...
To go in a phone that Exynos would have to be several voltage points lower and lower clocks, Cortex A15 wasn't really intended for phones and only maybe for tablets (hence Qualcomm Krait and latest Apple designs are enhanced A9 not A15)... Intel could get more performance in that Chromebook's power envelope with a down-clocked Core i3, it'd be expensive yes but desktop and laptop CPUs are different in their I/O etc, tightly integrated SOCs are a different beast.
Intel have got a process advantage meaning that they can die shrink Atom and clock it higher, they have new core designs etc coming through, so whilst the Samsung Exynos is fast now it might not look so good in comparison by next year and against the same generation parts.
The only really useful and informative face-off will come when we have an Exynos and an Atom, BOTH intended for use in a tablet in the same power envelope, both built into otherwise very similar tablets - then we can test performance and battery life hopefuly using the same OS (Windows RT maybe).