I think the long contract, 6 years?, was never going to be fulfilled as Kane and his brother thought they had what would in effect have been a get out clause of the "gentleman's agreement", which doesn't seem to have worked very well for Harry does it? Perhaps Kane's brother thought that a six year contract would make Spurs feel confident and give him enough time to find another club to pay Harry loads of money and then use the gentleman's agreement when the right club came along with the right offer.
However both Harry and his brother have to have known that Levy is a very, very tough negotiator and that unless it's in the contract it's going to be almost impossible to force Levy to agree to let Harry leave. This whole situation smacks of Harry getting poor advice from his brother who might not be the master negotiator he thought he was and has been schooled by Levy. Really Spurs players only tend to leave when Levy/Spurs want them to? I wonder if Kane will be sold next summer when Spurs have had a year of the new manager, see how that goes, where do we need to invest in the squad, who can we find for that, OK now we sell Kane to fund these moves.