Exactly, what he did was commit for the rest of his career. A four year contract would of gave him options in case of failure.
Now he's desperate, and people think his actions was him keeping his side of the deal. No, actually his actions was him realising that this deal is going to be very hard. He knows Levy is highly unlikely to budge on price and he knows that City are not prepared to go the 150 million. That isn't this clubs fault, that is Kanes fault. So if a better option comes then we have no obligation to stick with Kane. We do not owe Kane anything!