Nadal will be #1 even he lost tomorrow if Ruud/Alcaraz couldn't make the final, If nadal win tomorrow only, then Ruud and Alcaraz has to win the title to claim #1.
6-1 is his projected hight since he was still young that time, he just lower his projection to 6 as of now, his final hight could be lower or back to 6-1. Remember, he is still growing. lol