It won’t, but already scheduled activities won’t be affected for this change since scheduleToClose is recorded in event history (ActivityTaskScheduled)
I have shared a couple of link in response to your other question about workflow determinism Will tampering in terminating workflows result in some problems? - #2 by antonio.perez that might help with this question too.
For python, you can test your changes using the replayer, we have an example here https://github.com/temporalio/samples-python/tree/main/replay
Antonio