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But I am not sure whether that is what he really wants. He can go through some nostalgic moments then, I get that, but Sporting won't be very successful in the Champions League and it doesn't come down to a one man Ronaldo show or otherwise Al Nassr would be better off, too. He is still skilled and can score goals, which is what he proves a lot in the Portuguese national team, but I don't think he would be doing very well for Sporting in the Champions League. In the domestic league yes, but not so much in the CL as you need several superstars to reach something in that competition.
Currently, big teams in the Champions League such as Real Madrid, Man City, PSG, Bayern Munich and others are stuttering, only Liverpool have performed consistently this season, and Sporting CP are in a fairly good position as runners-up, Sporting have a great chance to secure a ticket to the last 16. CR7 also showed a good performance in the UEFA Nations League, which shows that CR7 is still capable enough to compete in the highest caste of the European championship. and financially it should be something that does not need to be questioned if the basis is love for the club.
However, on the other hand, Al Nasr and RSL also still need the services and popularity of CR7, because it cannot be denied that CR7 has improved the image of RSL and made the league the best league in Asia. So it is not impossible if CR7 decides to leave Al Nassr and RSL, then the popularity of the league will decrease like the French League 1 which has lost its main star K. Mbappe.
I am not sure Ronaldo has ever done anything out of love for a club. He was trying to pursue his own interest to the maximum, which is mostly about money and now it would be Sporting because nobody else would take him as he is a messy diva. But when Al Nassr offers him again 200 million, do you really think out of love he would go to Sporting? Of course not.
The teams you mentioned are struggling, but I am still careful to call Sporting a favorite now in the Champions League. They will go to the last 16 quite certainly, but so far except for Manchester City they haven't had strong opponents and even Tottenham was able to beat Manchester City away from home, but I would never argue that Tottenham were able to win the Champions League if they played in that competition.
The initial buzz was pretty big when Ronaldo went there, but as far as I can tell the buzz died down mostly. There are not that many people talking about Ronaldo anymore and while it is true that he increased popularity, the effect was temporary. They thought Ronaldo could get a snowball rolling, but that wasn't quite the case. Great players stopped joining the league because the Saudis made the mistake to offer Ronaldo half a billion for 2.5 years, which led other professionals to ask for a lot as well and that wasn't sustainable.