1. By people you mean "Google", and with a whole lot of money and a room full of some of the smartest people they could find. V8 is a whole department working full time, not a open source community-led effort. JS is also a different beast in a whole lot of ways. No, I am definitely saying "we can't make a JIT for Python that doesn't significantly impact single threaded scripts, retains significant backwards compatibility and doesn't massively complicate the cPython code". Obviously someone can make one, PyPy did, and it would be insane to ignore all of the HUGE problems they encountered (and overcame) while writing a JIT for Python. What makes you think cPython could do better?

2. It would make the reference implementation insanely more complex, to the point where it is no longer a reference implementation but a JIT implementation of Python. That's not cPython's role. For whos benefit is the requirement of a JIT? My apps run fine without them, and I don't need the memory bloat or startup cost associated with a JIT. If the community really wants another JIT they could fork cPython, find a room full of JIT experts and re-do all of the work PyPy has done, with all of the tradeoffs and problems they encountered. Nice idea.

3. "so small and short-running that neither slowdown or extra memory is usually an issue." - this is exactly the situation where a JIT adds a lot of overhead and becomes an issue.

4. So you want the best of both worlds, with no clear idea as to what magical person can make this happen (or even how) and you won't be happy until you can have your cake and eat it?