They were 60 seconds from getting into the Senate floor while Senators were still inside the room. If Eugene Goodman hadn't led them away, the day would have had a much worse outcome. This isn't even speculation, in the video where he confronts part of the mob and leads them away, you literally see the door to the Senate floor is wide open. It wasn't even sealed until after the mob had been led away. If the traitors had made it in, there would have been multiple more kills from Capitol police mowing down anyone that entered the room, or they would have stormed in fast enough to overcome the police and Senators would have been straight up murdered.
An actual change of government probably wouldn't have happened, but the day was incredibly close to being way worse than it already was.