Two Things I think that A10 Fusion could be:
1. A Dual CPU solution with an A10 ARM CPU and an x86-64 (intel or AMD) CPU
2. A way of offloading some processing from the A10 to a GPU
The A10 Fusion could well be a solution for MacBook Pro's where the laptop could contain a high performance Intel Processor and a high power efficiency A10. There have been rumours for years that Apple was looking to move CPU architecture to ARM based processors in their notebook line, in order to improve on power efficiency for battery life.
To entirely swap the CPU for ARM would mean that Apps requiring High performance such as Video, 3D Modelling and High End Gaming, would not be able to run with good performance under any emulation that Apple might deploy (Apple used an emulation technology called Rosetta when it migrated from PowerPC to x86 many years ago, this was possible because when that occurred the PowerPC performance was lagging behing that of intel chips in many areas, so when Apps ran under Rosetta, they weren't significantly slower than on previous generation macs).
Deploying two CPU's would allow Apple to accomplish a transition between CPU archtiectures, and provide extended battery life when using core productivity apps like Safari and iWork, as well as other apps like MSOffice (provided they were re-compiled for ARM), but still maintain high performance for using x86 or x86-64 apps or Windows (via Parrallels or VMware Fusion). Such a move would also mean that Apple could potentially use higher performance CPU's with larger power requirements (provided they can be cooled effectively within the chassis), because they would only need to be switched on when there was an application that needed those high performance functions.