#3 Manchester City's squad depth and risk of rotation
Even without Cristiano Ronaldo, Manchester City are already one of the best teams in the land filled with talent and class throughout. With Jack Grealish added to the mix at Manchester City, the competition for places won't be getting any easier.
The Premier League champions can easily field two entirely different starting elevens, capable enough of challenging for the title. Even then, they will still have a few world class players on the bench.
At the time of writing, Manchester City have Raheem Sterling, Riyad Mahrez, Jack Grealish, Bernardo Silva and Ferran Torres as options for the winger role.
This abundance of world-class wingers might result in rotation during games. If a situation arises when Ronaldo is unable to play almost every game of the season, it could prove detrimental to his ambitions.
#2 Cristiano Ronaldo may not be the ideal tactical fit
Aged 36, Ronaldo is not turning any younger. Even though he did what he does best last season and won the golden boot in Serie A with a whopping 29 goals, he looked out of place at times.
Cristiano Ronaldo can play down the middle and be as effective as he has been on many occasions with his national team Portugal. However, he has never been a part of such a demanding system as the one deployed by Guardiola at Manchester City.
Last season, Manchester City played with a false nine many times. Strikers in Pep's system often have to work their hardest by leading the pressing from the top.
This could affect Cristiano Ronaldo at Manchester City. It remains to be seen if he is ready for such a meticulously-planned system at this phase of his career.
#1 Manchester City switch could ruin his United legacy
When Manchester United played Sporting Lisbon in a pre-season friendly in 2003, little did they know they would come across a young Cristiano Ronaldo who would eventually go down in the history books.
With his quick feet and dazzling footwork, it didn't take long for him to endear himself amongst the United faithful. Cristiano Ronaldo won the golden boot in the 2007-08 season in which he also won his first ever Champions League medal.
However, the Portuguese was already on the look-out for a new challenge and ended up moving to Real Madrid, his dream club. At the Santiago Bernabeu, Ronaldo further elevated his status as one of the world's best players.
He returned to face United on a couple of occasions for Real Madrid and Juventus, his current club. Cristiano Ronaldo even scored against United for Los Blancos but refused to celebrate as he maintained he still had love and respect for the club.
Manchester United fans still celebrate Cristiano Ronaldo as one of their own. But a potential switch to Manchester City could ruin his relationship with the fanbase and the club that made him the star he is at the moment.
Rumors of Ronaldo being in talks with Manchester City have already incited a stern reaction from Manchester United fans all over the world. It could get even more intense from now until the end of the transfer window, especially considering how the plot is thickening by the minute.