Practical reuse of assembly is resourceful and this approach to portability quite cool (take a look at this non-portable approach to fixing up and executing an assembly dump[1]).
I wonder if the future of video game console emulation lies in recompilation, perhaps to an intermediate representation format for LLVM (similar to Dagger[2]).
[1] http://aluigi.altervista.org/mytoolz.htm#dump2func [2] http://dagger.repzret.org/
However, I am not a games programmer, and do not have any actual experience with console development. If there is anyone on here with experience in these areas, I would appreciate their thoughts on the matter.
As for where newer consoles are easier, the big thing is that there's more dynamic linking so there's more opportunity for high-level emulation of entire systems. Think being able to emulate entire OpenGL function calls rather than the raw GPU-specific register writes.