A costumized A4-1200 seems to be a good fit for a handheld.

But did Nintendo say that they were going to guarantee backwards compatibility with the WII U on their handhelds ? 

The term "architecture" can mean many things such as the design philosophy rather than adopting an instruction set architecture ...

I'm not sure anyone's entirely sure, that's why I keep stressing "IF", but my interpretation of it is that they want to use the Wii U as a starting point for Nintendo platforms being home to all Nintendo's games. They said something about that too IIRC.

The only way they can adapt their APU solutions to a handheld would be if they adopt soon 14nm manufaure process so they can low the power consumption a mobile rate... otherwise It will be not possible to AMD compite with ARm solutions, unless they create a mobile mix between current ARM processors and AMD gpus for mobiles that compite with the already experienced nVidia.

http://gamrconnect.vgchartz.com/thread.php?id=187080&page=1#

Thought I'd link this thread here as it is very relevant. I think that the chart is wrong partially since it seems that most people think the Wii U is 176 gigaflops not 352.