I love Ronaldo - but for the fees involved here, I think United should stay the hell away and concentrate on the future instead. We are talking figures that would make Monaco unable to refuse the same offer for Kylian Mbappe, who has a possible 14 years or so ahead of him at the top. We sold Ronaldo for 80M - we simply cannot bring him back for 100M+ - it makes absolutely no sense to me, no matter how awesome it would be to see him in red again.
He is 32, he is 33 in February - he is extremely agile and dynamic in his style, it is not the same as Zlatan who relies on totally different aspects in his way of playing. Ronaldo will deteriorate a whole lot over the next two years, and with age and his sprints and turns, injuries will happen for sure. He is the player with the best physical shape in the entire world, but even that will not matter much vs. age. Without the running and speed, Ronaldo will not be the monster he is today - and he has shown multiple times this season that his average level has fallen, which is only natural.
It would be great, but I also think it could be an issue. What if we sign him for 100M+ and he starts to become kind of average in a year, but still demands to play every single game and keeps us from grabbing another, younger player? There is the aspect involving marketing plans, merchandise and sales - but I don't even think those things will be even near the insane fee mentioned in the tabloids. You simply don't pay such figures for a guy at 32...