Cech would be a great keeper and can play until he's 40 personally. I hope we get a homegrown player in return. Would take any one of Chambers, Wilshere or Ramsey, would not take Walcott though which I feel is who Wenger will try and offer. Doubt Wenger would be that desperate for a GK though.
Chelsea aren't stupid, we know that if we give you a WC keeper you guys will be in a very good position for winning the title as there are very little differences between the strengths of our teams. So as much as Cech has been a great servant to the club and deserves to be playing, football is a business.