@all:
The 3DS CPU cant Emulate, even with its 2 Cores, the N64. The Architecture is to much different, that it could translate the Code into ARM Code and an emulation, as I said, is not possible.
By following that logic, the PSP couldn't even emulate properly PS1 since it lacks TLB and MMU... but isn't RISC on PSP a sligthly modified version of the one used on PS1? Yeah they could just "virtualize", but PS1 has a virtual ram system and a pseudo cpu handling (paging) those. Yeah it's possible because it's there, done.
While ARM differs from RISC (3DS to N64 case), and some smart guys have figured out, you can use modern GPUs to run sub-standard asm code (not easy!) for you. Since N64 wouldn't require 3D, only one core should suffice to handle gfx, the other GPU core handle framebuffer access, etc.
The problem I really see, is the custom microcode per N64 game. It uses hardware (interpreted on GPU, recompiled on N64 CPU) in a very specific way and basically it's so damn close to hardware that it'd have to be "emulated", or, "ported" completely to run on, a 3DS. [that is, if Nintendo really had to develop those in ASM, because they could probably have the game code in C or another language, then compile them ...]
And why would that make a difference? Dynamic Recompilation takes CPU instructions from one architecture, converts it to the different architecture, and saves it so it won't have to convert it when it runs across that instruction again. While some code would require 2-3 extra instructions to mimic a single instruction, there is also the possibility that a single instruction of the target architecture can handle an operation that would require 2-3 instructions from the source architecture. You take a look at something like the Corn N64 emulator for the PC, and you can see just how effective it is. I was able to run that emulator on a 233Mhz Pentium II at almost 60 fps with Super Mario 64, and the Pentium II is a far older architecture and not nearly as advanced as the ARM11.
I could run full 60 fps on a Pentium I 166mhz MMX with a legendary Voodoo 3 2000 agp card. Oh the nostalgia..