The fact he's fallen out with Simeone, if that's true, makes him transferible but still it doesn't mean Atleti will give him away that cheap. He's price should be around 28-30m.
I'm sure Tevez will stay one more year, Argentina's economy is bad and there isn't any club able to pay 5m a year even to Tevez. Tevez will stay at least until 2016 if not 2017 and then he'll go back to Boca to end his career.