If this is true, it would mean that Leverkusen are already preparing for the Champions league of next season, and if they have a player like Ronaldo with them on the attack, they can be ruthless. I doubt the move, though. I am not sure Leverkusen will be able to handle the wages of Ronaldo unless he decides to cut his wages for the opportunity to play again in the Champions League.
Leverkusen must be ready to play for UCL in the next season. That's why Xabi Alonso is preparing for the improvement of Leverkusen attacking now. Having Ronaldo in their attacking line is very interesting because Ronaldo has a great history in UCL. Even if Ronaldo will be 40 years old next year, every team in UCL won't underestimate Ronaldo.
Leverkusen should know how to handle Ronaldo's salary. Both Leverkusen management and Ronaldo must have a solution for the salary. I am sure Ronaldo won't ask his salary like he can get in Al Nassr. It should be lower than the salary of Ronaldo in Al Nassr. But I think it is not about the salary, it is about the possibility of Ronaldo to leave Al Nassr. He still has a contract with Al Nassr, I think he will be in AL Nassr until the contract is over.
Ronaldo already has a blossoming career in Saudi Arabia that has taken him two seasons to build; I am not sure he would want to abandon it. Next season is another time to try again with Al Nassr.
Ronaldo has a good career in Al Nassr but he always failed to win the trophy of SPL for Al Nassr. This may be the factor that Ronaldo considers to leave Al Nassr for the next season. But since Ronaldo always has a big motivation to win the trophy, he may try to stay in Al Nassr until he can win the trophy of SPL for Al Nassr.
Source: transfermarkt