If a batter has 2 strikes and all other conditions of the batter becoming a baserunner on a dropped strike 3 apply, can a batter swing “late” after seeing the ball get away from the catcher on what would have otherwise been a ball to “create” strike 3 and then advance?
No. If the ball had been a ball, it would already be called, and the judgment could not be changed. If the ball already was a strike, then swinging the bat would make no difference anyway.