Minor correction. The removal of the GIL is not disallowed by fiat. The removal of the GIL was attempted (via granular locking) and destroyed single threaded performance. That's unacceptable for a variety of reasons. In the same thread, Guido has repeatedly stated that the GIL was a tradeoff, and he would welcome anything that helped lessen it's impact/remove it should it be proven not to significantly harm Python's primary function.
If someone showed up with a patch tomorrow which allowed free threading without seriously breaking python, or crippling single threaded performance, or making extension modules impossible to write, I could very well see it getting in. In reality, doing this requires a serious reworking of the interpreter (ala unladen swallow) to make it even feasible. There's a lot of things the GIL actually helps, for example the ease of writing c-based extension module, unfortunately they come with a price.
The price is/was seen as an acceptable tradeoff, and I think it has served it well, even if if it disappeared tomorrow no one would shed a tear.
Minor correction. The removal of the GIL is not disallowed by fiat.
To piggyback: don't forget that CPython ≠ Python. The GIL is an implementation detail of CPython, not a feature of the language. Other Pythons -- Jython, for one -- have no GIL.
BTW, if you'd like to chat more about concurrency, I'm around all weekend (although I'm late getting to the University of Belgrano today). As my comments during your talk yesterday indicated, I think you're pretty off-base arguing that people aren't trying out interesting concurrency solutions in Python — ZODB is a (somewhat broken) STM that's been production-stable for many years, and Stackless is specifically targeted at actor-based modeling.
So I think people in the Python community have actually been way out in front on these issues. It's just that most people use Python for production work, not research, so the researchy stuff doesn't make it into the mainline.
If someone showed up with a patch tomorrow which allowed free threading without seriously breaking python, or crippling single threaded performance, or making extension modules impossible to write, I could very well see it getting in. In reality, doing this requires a serious reworking of the interpreter (ala unladen swallow) to make it even feasible. There's a lot of things the GIL actually helps, for example the ease of writing c-based extension module, unfortunately they come with a price.
The price is/was seen as an acceptable tradeoff, and I think it has served it well, even if if it disappeared tomorrow no one would shed a tear.
Also, braces aren't a feature :p