Must depend on the GA. I thought the answer was no but others on here are saying yes.

When I take WN on a paid fare it's usually DTW to MDW. Short flight but I arrived at the airpoert and my flight was showing late by an hour (Ended up being a couple hours late and we left DTW well after we should have been at MDW and I could have driven it faster that day). The flight before mine was also very delayed and I requested to be put on it and was told I would have to pay for an upgrade to full fare. I don't have a problem with them charging that if I get to the airport early and my flight is on time but when your scheduled flight time is delayed over an hour and if there is room on an earlier flight they should allow you on it. It isn't costing WN anything and in this case the early flight had seats and my flight was the last flight out and every seat was full, so they would ahve the possiblity of filling that seat with a full fare.