With the personal pressure from Mbappe (reject to renew his contract with all offers from PSG), the odds that Real Madrid have Mbappe is increasing. Especially when Manchester City can not buy Harry Kane.
If PSG sell Mbappe, they will have two strikers to choose, Kane and Ronaldo. Kane is better because he is younger and will have longer career than Ronaldo. But Ronaldo has a cheaper cost and PSG can use rest money to do other things.
Kane probably won't leave Premier League so the scenario with which Ramos, Ronaldo, Messi reunite all in PSG is very possibly.
If Cristiano Ronaldo finally moves to PSG, it is likely that Kylian Mbappe will be released by PSG and potentially join Real Madrid, and I think this is a win-win solution for PSG, Mbappe, and Real Madrid.
But there could be a surprise if it turns out that Real Madrid brought Ronaldo back to Santiago Bernabeu. Even though Ronaldo is no longer young but he can still contribute a lot to Real Madrid (at least for the next 1-2 years) and of course he will adapt quickly because he has played at Real Madrid for a long time. Other than that, to sign Ronaldo will not be as expensive as Kylian Mbappe, so Real Madrid can save money to buy another player (because Real Madrid really needs a center-back).
Buying Ronaldo would be a mistake for Madrid and Psg. Ronaldo's best years are in the past. And his age is big. It is more profitable to buy Mbappe. But Psg wants too much money for a player who has one year left before the end of the contract.