Cristiano's signed a mega contract with Al Nassr he's staying for 2 years. I don't know they've given him shares in the company he would've stayed because other teams can't give him mega contracts. If Al Nassr don't win their SPL it won't be considered successful signing.
I'm sure it is not only about winning a trophy of Saudi league or other competitions. Al Nassr signed Ronaldo because Ronaldo can also increase the popularity of Al Nassr and even Saudi league, too. Even if Al Nassr still can't win SPL trophy, Al Nassr must get a significant improvement in merchandise sales besides its popularity. This is something impossible to do by another player. So, I think Al Nassr has been quite successful with Ronaldo.
At least they won in popularity.
If they really want to become a champion, they have to sign top defenders because Al Nassr too focus in strength.
Of course, they are quite successful in improving the popularity. Now, I'm sure most people in the world know Al Nassr. And more famous players want to join Saudi league because of Ronaldo's effect, too. Dude, I believe Al Nassr wants to improve their defense. They should have a plan to buy some stronger defenders. It probably depends on the new coach, which players to expect by Jorge Jesus. Let's wait for the new coach to consider their target for the new players.