Many discussions of a surviving PLC involve reforms that curtail the power of the Senate or install a strong king or hereditary dynasty. Is it possible to go the other way, and have the Sejm abolish the monarchy entirely, even as a fiction? To have Poland-Lithuania ruled by elected officials (be their titles Roman or native) with set terms?
Would a supremely incompetent or unpopular king suffice? Or must there be a more severe social upheaval?
And would a truly Republican Poland-Lithuania be better or worse than the OTL institution or a hypothetical strong monarchy at suppressing the centrifugal tendencies of the szlachta?