You didn't think ARM chips will stop at having only 4 cores (or 5 in Tegra 3's case), did you? At ISSC (International Solid-State Circuits Conference) this February, Samsung will present an 8 core, or rather two quad-core clusters of Cortex A15 and Cortex A7 CPU cores, in a big.Little configuration.
Big.Little combines very low-power cores like Cortex A7 with very high-performance cores like Cortex A15, for a well optimized mobile experience and balanced battery life. The quad core A7 cluster which runs at 1.2 Ghz per core, and should have the performance of a theoretical quad core Cortex A8 chip, while being several times more energy efficient, will be used for most daily tasks that don't require maximum performance.
The quad core A15 cluster on the other hand, which will run at 1.8 Ghz per core, and have 2 MB of L2 cache, will be used when maximum performance is needed, such as games and browsing, where you want your web page to load in an instant, especially over high-speed connections like LTE, where the processor might currently be the bottleneck.
But why have 2 clusters of quad cores and not 2 clusters of dual cores? For now it seems this chip will be targetting tablets, which makes sense, especially on a future Galaxy Note 10.1 tablet, where they are using true app multi-tasking, which needs high performance quad core chips for the best performance.
It's possible that for the time being we'll only see a chip that contains 2 clusters of dual core CPU's for smartphones (2 A15+2 A7), although there's no rumor of this chip existing yet, but it seems like the natural progression for Samsung Exynos 5 Dual that currently lacks the A7 parts. My guess is we'll be seeing this 2 cluster dual core chip in the upcoming Galaxy S4 (although perhaps with A15 overclocked to 2 Ghz), and then the quad core 4+4 version in some upcoming tablets mid 2013, like Galaxy Tab 10.1 3.0 and Galaxy Note 10.1 2.0.
Exynos 5 Dual is already the fastest mobile chip in the market right now, by far, for 2 reasons: it has the highest performance architecture, and it also has the highest clock speeds. These 2 combined give a knock-out punch to all the other chips in the market. But this chip may be a little too much for a smartphone, which is why Samsung is waiting for the big.Little version before using it in a smartphone.
Things should get very competitive next year between Samsung, Nvidia with its Tegra 4, and a future version of the S4 Pro chip, although I expect Samsung to win out next year, because of this powerful combination of 4+4 A15 and A7's. Normally, I'd expect Samsung to continue having the best GPU in Android devices, but Nvidia might surprise us with their revamped GPU architecture next year.