Possibly relevant -- Nim has a compile-time warning for bare exceptions, initially enabled by default [1]. I think Nim-core changed their mind about this being a good idea a few months later: https://github.com/nim-lang/Nim/pull/21728 (though the message still says "The bare except clause is deprecated" if you do compile with --warning:BareExcept:on - I think the urge to actually deprecate has gone away).
I think for Python, rather than breaking bajillions of unpublished lines of code they should start with a more tentative & minimally invasive environment var/CLI switch opt-out warning that says something like "may be deprecated" where even the Python ./configure script lets you opt out at Python interpreter-compile-time. Measure the scope of the porting problem for a few years before trying to decide on The Plan for something that might be too disruptive.
I think for Python, rather than breaking bajillions of unpublished lines of code they should start with a more tentative & minimally invasive environment var/CLI switch opt-out warning that says something like "may be deprecated" where even the Python ./configure script lets you opt out at Python interpreter-compile-time. Measure the scope of the porting problem for a few years before trying to decide on The Plan for something that might be too disruptive.
[1] https://github.com/nim-lang/Nim/commit/91ce8c385d4ccbaab8048...