maybe Mbappe stay at PSG can help his team win the UCL title (even though it's impossible) but the fact is that PSG will still have difficulty if they only rely on Mbappe because they are not strong enough if they only rely on one player without having a solid line up. meanwhile, to be able to win a title at UCL you have to have strong cooperation, whereas PSG doesn't have solid cooperation for me.
PSG has some of the best players in Europe, I don't know why people feel that without Mbappe the club will underperform. No doubt the French striker is one of the pillars of the club but we still have to recognise players like Lee Kang-in, Achraf Hakimi, Vitinha and others who have contributed to the club. The club has given Mbappe all the support he needs but the only problem he has with PSG is his refusal to sign a new contract.
From the club's performance in the UCL group stage where they managed to qualify, I don't see them winning the Champions League. But in sports, we cannot say never because we have seen teams with less quality than PSG winning the Champions League. I am sure that the French young player might decide to remain with the club if they win the UCL because the trophy will boast Mbappe's ambition of winning the Ballon d'Or.
regarding Mbappe move in january, he won't be moving, but if PSG keeps him until June, it looks like he will leave as a free agent and PSG will suffer a loss if he leaves as a free agent.
There has been no news of any club that is willing to sign Mbappe this month. Real Madrid have made it clear that they have ended the bid to sign the French player. So there is every possibility that he will remain in the club till the end of the season.