Absolutely not, this would be horrible for the Pandora 2.
Dual core is a maximum, an octa-core would be so inefficient that there's almost no hope of being able to overclock. High core counts help multi-tasking, not emulation performance. For emulation, you want your core count to be low and the core clock high. It doesn't matter how many cores you have because emulators are only able to take advantage of one CPU core in most cases (some emulators for PS2 and GameCube are written to utilize two cores, which is why I said dual-core). Core clock is absolutely vital to the performance of emulators, and with that many cores crammed into one SoC there's no way you'd be able to clock it to a reasonable speed without melting the device.
Not only would emulation be laughably slow on that thing, it would also be an extreme power hog and probably wouldn't overclock at all. It'd also require some sort of active cooling mechanism, because that thing will run HOT under load. I will cry if the devs put anything more than a dual-core in the Pandora 2, let alone that monstrosity.
More cores don't make the system less efficient just by existing. The cores you don't use can be turned off completely. When they're off they don't contribute to power consumption at all, nor do they impact the peak clock you can get.
The reason why there are 4 Cortex-A15 cores and 4 Cortex-A7 cores is not because Samsung expects them all to be running at the same time in any normal scenario, but to give you more scheduling flexibility which improves power consumption. For instance, emulators that run fine on CC Pandoras can use a single Cortex-A7 clocked at under 800MHz, with another Cortex-A7 core periodically active to take in background stuff to prevent anything from stealing process time from the emulator. More demanding ones can use one or two Cortex-A15 threads while delegating other stuff - like 3D driver coaxing, frame post-processing, audio handling etc on Cortex-A7 threads. Or anything that uses a software 3D render (DS emulation for instance) can divvy up the task among multiple Cortex-A7s. A single Cortex-A7 on Samsung's 28nm will tend to use significantly less power than the Cortex-A8 in the OMAP3 and even DM3730 Pandoras, while offering almost as good perf/MHz for a lot of tasks.
IMO a 2x Cortex-A15 + 4x Cortex-A7 solution makes a lot of sense and 4x Cortex-A15s seem like overkill, but if they have the die area to spend it doesn't hurt that much, unless it could have been better spent on L2 cache. The Cortex-A7s are comparatively tiny so having 4 of them barely makes a difference.