84 million XBox 360s in the wild so it may be a bit late for that :-) Consoles have very predictable patterns of execution and only run a limited set of software so it's not so much a problem there. It would be a much more serious problem if this was a chip for a general purpose PC.
The 360 didn't open up the ability for titles to generate their own code and run it. Some internal features of the 360 did (the back compat stuff, and some other projects I can't talk about), but in general you couldn't JIT without some special permissions bits.
