I also feel that Mbappe will join Real Madrid. There must be a reason why Mbappe refused to renew the contract offered by PSG (even though the salary offered was bigger than before). Real Madrid is one of the biggest teams in the world, and many players want to be able to play for Real Madrid (maybe Mbappe is one of them).
If Mbappe really joins Real Madrid, then Real Madrid's chances in the title race will be even greater (they just need to find a strong defender to replace Ramos).
It would be a bad decision from Mbappe because PSG are moving closer to Champions League title. They only need to keep up their good works and a bit more luckiness in their matches to win Champions League.
Real Madrid now are in the early of a new generation and Mbappe will join a club that is similar to PSG a few seasons ago. I think Mbappe will get all he want in PSG. Just a bit more time, a few more seasons. Mbappe is one of most important players in PSG and he will get same position in Real Madrid but without big difference in his position, he should not leave PSG.