Not before Putin's regime disappear or unless Snowden himself start to become danger. I don't believe Putin will trade him under any circumstances. More likely

Not before Putin's regime disappear or unless Snowden himself start to become danger. I don't believe Putin will trade him under any circumstances. More likely you'll see Crimea traded. Asylum for Snowden it's wasn't just foreign policy act, but more act for Russian elites: we provided asylum for almost #1 on US list and we he is safe. Whole regime built on rule that any loyal person in elites is safe no matter if he's murderer, pedophile or any other kind of criminal. Just think about Magnitsky case. It's was just a bunch of criminals who wasn't even part of Russian elite, but Putin didn't betrayed them even after it was clear that would cause significantly damage to whole county economy. So giving Snowden would sent signal to elites that they and their capitals no longer safe. It's would be deathly for regime.