The most important points are, Snowdens passport has not been revoked. Its not even legal per the US state dept website to do so.
He has a completely valid US passport to travel with. What he IS doing is stopping in places long enough to tantalize local officials with the data he has to see where that might lead.
Unless he travels to a country that the US can throw Interpol at him, he is a free man. That sounds easier than it really is. But its still a true fact.
Rather than speculating that he's in a Russian suburb, being drugged by alleged KGB thugs, it might be more constructive to realize he could easily take a private plane out of Moscow and reach his destination if he has one.
No entity including the US is going to kill the golden goose when it laid its egg before it could be hatched.
As Julian Assange said, no state will be able to prevent the release of the complete trove of information.
So if you want to play international poker, you had better be holding the cards.
Place your bets....