Ok well let's say we get 100 million for Kane in the summer. How do we replace him? You won't get as good a player as Kane even if you spent the full 100 million quid you got for his sale (at least not one that would want to play for Spurs). Does it not make more sense to keep Kane at the club for as long as possible even if you don't get money for him if he leaves the following summer? Surely that benefits the club a lot more than one big pay out for an irreplaceable player.
You won't, but you might get 2 good players that want to be at the club and who might stay for a longer period.
Anyway, it's a tough question for the board if he doesn't want to renew. You can gamble on him changing his mind in summer '24 and re-signing. But he might just go free at Real or something. And if Spurs don't achieve anything with him next season (like a top 4 finish) that's a £100m wasted.