Real Madrid have no other option but to approach Mbappe at the end of the season so they can find a suitable striker to replace Benzema.
Mbappe has a high release clause, but one that Real Madrid may be obliged to fulfill if they are interested in Mbappe. It's honest that Real Madrid were very disappointed when Mbappe chose to stay at PSG this season, but that is the player's right even if many people think he has been influenced by big money.
So now Real Madrid have a chance to make that wish come true, but they will have to spend a lot of money on Mbappe if PSG are willing to sell him next season. Mbappe is a great striker, and he deserves the high price.
Of course, Real Madrid must spend a lot of money if they still want Mbappe. But I agree that Mbappe deserves to be paid huge money since he is one of the best strikers in the world and he is still young, too. I am sure Real Madrid will take a big advantage if they successfully sign Mbappe in the next transfer window. Having Mbappe, Real Madrid attacking line will be very strong for the next season. And Real Madrid won't be afraid of their main striker for the next 10 years, Mbappe has a long future since he is still 24 years old.
However, the problem is how to ensure PSG releases Mbappe. I think it will be difficult to negotiate with PSG, they will try to keep Mbappe as long as possible.