I would expect fringe players like Jenkinson, Debuchy, Campbell and Sanogo, if he is still here, to leave.
But if it's first team players, I'll go for around three or four, If you are counting Sanchez not signing a new contract.
I wouldn't be surprised if Sanchez doesn't sign a new contract and is sold.
Chamberlain, Gibbs and possibly Perez might be moved on as well, even though they are more than useful squad players, and Chamberlain could still be a very good first team player.
I would rather see Walcott go than Chamberlain, and I wouldn't be to bothered if Ramsey went as well, as long as a world class midfielder comes in, as well as a world class striker.
But I'll go for Sanchez, unless we are willing to run down his contract and let him go for free, Gibbs, Chamberlain and Perez to leave.