Actually, I dont think F1 has ever had as few replacements as for this season. The only new face is Buemi, who replaces Vettel, who in turn replaces the only driver who actually left: Coulthard.
Next season will se bigger changes, I reckon. Exit for Piquet, Barrichello, Fisichella and maybe Nakajima and Bourdais- and even Raikkonen might decide its time to drink more and give the middle finger to the media circus. I think Kovalainen needs a strong season too.
The only drivers (IMO) that can do what they want this year without getting sacked are Alonso, Kubica, Hamilton, Vettel, Massa and Rosberg. Oh, I accidentally put them in a not so random order.