I don't think Ronaldo will ever become a coach. He would be rather the guy who owns part of the club or become the president and do more things in the background. His lifestyle and all the entrepreneurial projects he has make it unlikely that he would work as a full-time coach. Of course nobody can know it for sure, but I doubt he is the kind of guy who would want to work 365 days a year as a coach.
There is also this wrong idea that every great player can be a great coach. Look at Maradona, he was so bad as a coach. Ronaldo has all the top qualities as a player, knows where and when to run and how to execute everything on the field. But I don't think he is a strategy guy like Guardiola. He is also not like Zidane or Ancelotti.
President is more what resembles him. He could boss around a bit and he wouldn't have to be dealing with daily issues like a coach has to.
I don’t know whether or not Ronaldo will want to be a coach when he retires that is a decision for Ronaldo himself to make but from my observations and opinion I think Ronaldo will make a good manager if he decides to venture into coaching, he has the qualities of a leader and a coach. It is likely he might want to be part of a owning a club even since he already has 15 percent of Al Nassr ownership. We will see what the future holds for Ronaldo when he retires.