Imho, given the publicity of the issue, there's no way the current US judicial system could find Snowden guilty of treason without creating a huge domestic and international scandal. Politically, this would turn into an enormous backlash. To maintain the image of a state of law, the US has no other choice than prosecute, but the outcome will turn out as either:
- a mistrial, followed by a strong attempt at burying the case somehow (probably with other events)
- a non guilty verdict, with spin doctoring to display the whole thing as a demonstration of the fact that the US constitution and overall legal system is sound,
- a "guilty" verdict, but with so much attenuating circumstances than there will be no significant sentence
However, for Snowden, I doubt that he will be able to find a job again in his line of work, after breaking the "ethic rules". What security company would hire a (skilled even) security analyst (or whatever Snowden was actually doing) if he cannot keep it shut on the internal practices? The scope could widen to any entreprise actually.