“We do not want another Python 3 situation, so any changes in third-party code needed to accommodate no-GIL builds should just work in with-GIL builds (although backward compatibility with older Python versions will still need to be addressed). This is not Python 4.”
The Steering Council intends to accept PEP 703 and drop the GIL. The plan is an experimental build in 3.13, a supported build a year or two later, and no-GIL as the only build in as much as five years. They also reserve the right to roll it all back. Every C extension maintainer now owns a thread-safety audit nobody is paying for.