I keep coming back to this decision to let Sergio leave in March.
I don't believe they would do that unless they had someone lined up in principle agreement with the player, agent and club. You wouldn't make that decision that early unless you knew almost for certain someone was coming in.
I can see them doing it if Messi's camp gave them a nudge nudge. I can see Dortmund privately saying he's there for £Xm before the buyout clause comes in next summer.
I don't see Kane and Levy agreeing something that early.