The standard build that you get at python.org will work exactly as now (so with a Gil).
The disable-gil build (which will most likely be available through conda or similar) will have the option to run either with the GIL or without. It will automatically detect extension that are not compatible and switch to Gil mode but you can override this with an environment variable.
Basically there will be two build mode.
The standard build that you get at python.org will work exactly as now (so with a Gil).
The disable-gil build (which will most likely be available through conda or similar) will have the option to run either with the GIL or without. It will automatically detect extension that are not compatible and switch to Gil mode but you can override this with an environment variable.