Neither Cazorla nor Walcott would be dropped for Nasri. The former is just as good on the ball with more end product. The latter is our form striker.
If anyone got dropped for Nasri (doubtful) it would be Podolski or Giroud with a consequent changeup of the front six. I can't see that really helping though, since both of those are effective players at the moment with a good niche in our side carved out.
If Nasri wants his career back he should find himself a second tier club that will start him in midfield.