I think Nasri has already been replaced. By Gervinho.
The hole which will be hard to fill will be Fabregas. His goals + assist average at around 30 per season. There are not many like him around. One of the best in his position.
Nasri had a great 1st half of last season, but was nowhere to be seen in the 2nd half. He is approaching his prime no doubt but so is Gervinho.
Crisis? What crisis?
The greatest act of bravery is chancing a fart while suffering from diarrhoea