Well... Mathematically Massa down in 9th place is still in the championship. However he'd need to win all the remaining races with Alonso norm scoring at all and even then he'd only equal Alonso's tally.
I think realistically at this point the championship is between Alonso and Vettel, on evidence of recent form you'd have to say that Vettel is favourite but form has fluctuated quite widely so far in 2012.
I think Kimi is now realistically out of it, unless Lotus make a big step in getting the best out of that car and consistently. He'd really need to win at least at least 2 of the remaining races and finish on the podium in the rest to stand a chance.
Similarly Mclaren are probably out of it... They've got a quick enough car but setup errors and reliability glitches are putting a lid on their championship aspersions, they should focus on trying to close the gap to Red Bull in the constructors.
I think that possibly the biggest change in the order could be Sauber, they have a real chance of chasing Mercedes down and overtaking them.