Yeah, the results haven't worked out for him this year but his qualifying has improved so much this year. Last year I remember he was more often than not behind Sergio, but this year it's the opposite.
He's had two good seasons already in F1 and one season which isn't bad, but not gone as everyone would have hoped for. I don't see why he should be dropped. It's a shame, if he was the one who scored a couple of podiums, he would have been considered by McLaren.
It seems that Kobayashi is, sadly, becoming the Heidfeld of this generation. Both of them were considered to be talented when they came to F1 (Heidfeld for his F3000 results, Kobayashi for when he replaced Glock). Both drove for Sauber and had a good teammate who got promoted to McLaren (although in Nick's case that was much more painful, as he was their test driver). When Nick got a chance of driving for a top-tier team, it was either uncompetitive (Williams 2005) or he was overlooked because of his teammate's performances (BMW Sauber 2008).
I hope this will not be the case for Kobayashi. I would love to see him on the top step of the podium one day.