Several things to note,
Levy is driven by £ only, he has a history of leaving it until late, & pocketing the cash. He will be left with a disgruntled player if he doesn’t sell, whose peak value is right now, because he will be too old in a years time.
Kane has several options if it’s a “now or never” window to leave, he can put in a transfer request, say fuck the bonuses, and try to increase the pressure on Levy, if that doesn’t work, he can invoke the Webster ruling, & pay his way out of his contract, even telling Levy that he’s going to do this should have the desired effect, I know we’ve not seen this in the Prem, but Fernandinho paid £4m of his own fee to move to City, if Kane truly believes it’s about winning trophies and furthering his career, he needs to do everything he can to do so, not play both sides, not worry about reputations & bonuses.