Mbappe, who has a year left on his current contract at the Parc des Princes, is reluctant to extend his stay in the French capital.
The 22-year-old is said to be eager to join Real Madrid before the end of this summer’s transfer window which will be due on August 31.
The La Liga giants have tested the waters with €160 million in a bid to sign the 2018 World Cup winner but the Parisians quickly turned the offer down.
PSG risk losing Mbappe for free next summer and Cundy has urged them to cash in on one of their prized assets to fund the transfer fee for Kane, who is also pushing for a move away from the Tottenham Hotspur Stadium.
The 51-year-old said: “If you’re getting offered this money for a player who has less than a year on his contract, and you turn that down, that makes no business sense.
“He’s going to leave, he’s going to dig his heels in, and the relationship between the pair looks like it could break down completely.”
Cundy added: “PSG should take the money and they should sign Kane.
“If they want to go and sign someone now, they really want to replace him, Kane is as good as anyone they can get right now. “The only problem is whether Kane wants to go to PSG.”
