One thing not many people (including Kane) seem to've realized is that should his current wages of "up to 200k" a week become outdated, as we've seen football wage scale in the PL get smashed in the last few years - Kane, being tied to a 6 year agreement will have basically no power to renegotiate them with Levy...
If the PL wage scale leaps up again soon (which it probably will), and the top strikers across the league are all earning 400k a week, Kane is tied, for 6 years, to an "up to 200k" a week contract.
It seems an incredibly foolish move for Kane and his advisors.