If Kane is not traded this summer, he will go free next season. It's probably better to get 100 (90 or even 80-70) million than to lose a player for free. I doubt that a club like Tottenham can afford to "pay" for any player 100 million (plus salary) a year. But that's exactly what will happen if Kane stays for another year and then leaves - it will turn out that Tottenham will lose a player and not get 100 million.
Harry Kane has done a lot for Tottenham over the years. I don't think he owes the team anything, and I don't think the team has any reason not to let him go. This Kane issue is comparable to Mason Mount's at Chelsea. It will be impossible for any team to pay $100 million for Kane, especially when they are aware that his contract is due to expire and he will be available as a free agent next season, so why don't Tottenham accept the price of any team interested? Tottenham should just agree to any price and not take the chance of making money off of Harry Kane, since I'm confident they will get more than $50 million for him.
In the afternoon I saw on the news that Kane and Bayern had reached an agreement and now Kane only wants to go to Bayern and the only problem is the position of Tottenham. The most funny situation since Bayern is a tight-fisted club and they definitely won't pay as much for Kane as Tottenham wants. If this news is true, then we are in for an exciting show