Apparently, Southwest is still evaluating whether or not they will extend the open middle seat policy, past the end of October. The advisement is to basically watch their website and social media for updates.
If you have travel booked on Southwest past October 31, and it's announced that middle seats on Southwest will no longer be blocked after that date, will you cancel your Southwest flights? As of right now, only one airline (Delta) has confirmed that they will continue to block middle seats on their flights, till the first week of January 2021.