Ferdinand is sidelined with a back complaint believed to be at the root of his other injuries.
Capello said: "It's too far away to decide about Ferdinand. Look at Italy, Alessandro Nesta was injured for a year, now he's the best and everyone is saying, 'Please come back in the national team'.
"It's not a worry if Rio is not fit in January because he can be playing in March or April. Rio has told me lots of times that he will be fit.
"I hope he is right because it is really important that the best players will be fit."