I don't agree with the crazy transfers in modern football but an key play for a team pushing for top 6 and a world cup winner must command a fee of around 100m. I'd feel a little robbed if we only got around 60m for him.
If we get a fair price it's an our interest to get the deal done as early as possible. They'll be no sour grapes from me, his spell with us has been excellent and I don't begrudge him a chance at winning the league.
It's probably best to sell him at his peak. An underwhelming season with us next year might knock 20m off his value. I also think he's earnt the oppertunity to join one of the big boys.