If Real Madrid fail to sign Mbappe, then surely a contract with Kane will be signed. Moreover, there was information recently that Kane was telling his Tottenham teammates that he would move to Real Madrid. Real Madrid, after Benzema's departure, needs a super scoring striker with experience. In addition, recently, not least after working with Mourinho, Kane has improved his assistant skills quite well, which could be useful when playing in conjunction with Mbappe.
I think that madrid has been saying if the club will not sign mbappe even though PSG intend to sell him this summer. It's caused by real madrid shall have control its financial to comply with FFP.
Im sure mbappe will be priced as high as bellingham. It's caused by PSG bought him with a very high price from monaco. PSG is not willing to lose a lot of money. that's why selling mbappe gonna be the best way to recover at least 50% from the amounts used by to bought him from monaco.
I think that even kane will not also join in real madrid. His release clause was very complicated and expensive. Kane is not having long time remaining to play in the professional football.
I prefer for real madrid to get a young talented striker rather than try to sign him with non sense price from totenham.