There probably won't be any prosecution because Snowden most likely defected to the Chinese government. It may have been his plan all along. I'm sure there are a lot of people out there who would love to leave their families, and be considered a hero by the general public, and live their life comfortably in another country. Given all the secrets he probably has that he hasn't released, he would be a very valuable resource to China.

This is something someone in his position would know how to do, safely, and with a great reward to himself, given that he's probably read the outcomes of hundreds of informants defecting to other countries.

And given his CIA background, he knew enough about propaganda to know how to sell it to keep his family from being shamed by being related to a defector.

The idea that a guy that's smart enough to make 6 figures after not graduating high school can't plan far enough ahead to explain why he went to China is ludicrous. He's simply not telling the truth about his motives.