Seems there is quite a consensus on Trulli and Heidfeld leaving already. Agree on Heidfeld, as I don’t know where he would go except to drive for BMW in DTM.
I would think DlRosa stays with McLaren as tester. And I think Webber will stay as well, with Red Bull. Glock would not quit. He can stay with Virgin, as they might improve with McLaren help. It might even be a way for him to end up driving for McLaren in the future!
Even Trulli might stay, as Lotus keep repeating that its their car problems holding him back. I guess Liuzzi might be out of a job depending on what the HRT owners are doing. And Narain might be out of a job (or end up test driver at Williams again?) alternatively Sutil will be dropped and ends up in DTM as well.
So my best guess: Heidfeld, Liuzzi and Sutil