In other seasons we see competition between Al Hilal and Al Nassr and either of these two teams become the champion but this season instead of Al Nassr the competition has been strong so far with Al Ittihad. Al Nassr doesn't have a very good chance of returning to the league this season at least, so I now think either Al Hilal or Al Ittihad will win the Saudi League title.
As a club and a team, Al Nassr has to fight their matches with players and coach, not only with Cristiano Ronaldo. They win and lose their matches with Cristiano as one of their players or without him, and should never let this old super star player affects their squad negatively. With high ego of Cristiano Ronaldo, when things turn bad and exceeds his controlable ability, he will react very unfriendly, harshly and it will destroy Al Nassr internally.
Now things are good with him, and Al Nassr can look at other things like their defense weakness and try to fix it. If they can not do it, they will not be competitive enough to win Saudi Professional League.
But it wasn't noticed the way you describe it because the goal was to bring in a player who is bigger than the club with the objective to make the club bigger. Everyone thought that when Ronaldo signed his contract for Al Nassr that they would instantly win titles. But that was a big fallacy from the first day until now. Ronaldo did what he is known for, he scored his goals and celebrated them and then the fans learned his weird scream after he scores, but there was nothing more he could achieve with Al Nassr. He isn't even the best goal scorer anymore and I believe he is looking forward to this contract being terminated unless they will extend it with the same insane conditions. His idea always was to take the money and live the best life afterwards. He was rich before he signed the contract, but half a billion in addition to what he already had doesn't feel too bad.