We will not replace him. Silva is a once-in-a-generation player, the best I've seen in a City shirt along with Bell. What we will do is limit the damage, by bringing in fine midfielders with years ahead of them – Gundogan is the first of the crop. But as I've said before, a player of Silva's sheer footballing intelligence can play at top level until about thirty-five, if he's managed correctly (as he is being at present – not played into the ground, as he was being by Pellegrini).
There were more than a few silly posts on this forum towards the end of last season about how Silva was washed up. Could've been rag impostors, of course, and wishful thinking.