@Max B
He has come up thru Spurs's ranks, so he will have strong ties to the club. But if Spurs aren't matching his ambitions and or don't win something, then he'll be off. He is the one player Levy cannot afford to sell even if the offer is £100-120m, Alli & Eriksen, they came from other clubs, so the likelihood is, they will move on to pastures new at some point in their career.
Also once Spurs move to the new stadium and Levy doesn't up the pay scale, then I think that maybe the only thing that would make Kane considering leaving because while playing for the club you love is great, but you also have to be paid as a top player and that is what Kane is in England at present.