Right now Mourinho loves Benzema so they don't need Robin, Barcelona (Robins first choice) have Messi in his position, so they don't need him. Juventus are undergoing a corruption trial, Milan's owner is wanting to save money, and Inter aren't going to be winning anything anytime soon. United aren't willing to pay top dollar for him (Ferguson likes Welbeck and does't want a repeat of Berbatov) and PSG are in a crap league. Add to that his injury reputation, poor euro's, only having one really good season, age, only one year left on his contract and he doesn't seem worth splashing out on which Wenger needs to consider selling.
His only real option is City but its touch and go whether they are even really interested with Tevez, Balotelli and Aguero in their team. He chose a really shit time to leave. Most likely scenario is he runs down his contract.