Whether Ronaldo goes to Roma or not, one thing is certain for me that Roma should make their squad more powerful in the summer. They made a big improvement generally last season.
That's what they have to do because the competition will be tougher next season. Milan, Inter, Napoli and Juventus will be fighting for the title and they look set to continue improving their squad with some new signings. If Roma don't do it, then I'm sure Mourinho and his players will find it very difficult to break into the top four next season.
The possibility is still there but actually I'm not quite sure whether Ronaldo will return to Serie A or not because there is indeed a past with Juventus which of course will have some intersections later.
But there is still a possibility because in this case Ronaldo's transfer is sometimes unpredictable, like when from Madrid to Juventus without much news and from Juventus to MU suddenly it is not impossible indeed if he goes to Rome in a fast time and without the media knowing.