Why would Palace accept 40m though? No chance at all. We think he is worth around 40-55m but to Palace it's much more. He is singlehandedly the difference between relegation and staying up if you saw the impact of him in the team vs their win/loss ratio. He is too important for them to consider selling on a cheap and not to mention they manage to get 55m for a youth RB.
If our finances is managed properly past few years this transfer would have been easy peasy. He is probably the only one linked in the entire transfer window they might elevate us to a slightly higher level although his injury record will be a huge concern.