At this time, I think any attempt to bring Snowden to trial would ignite a firestorm in this country no matter what verdict was reached. I think that will be the situation for the rest of his life.
There can be no question that he violated USA laws.
But there can also be no question that his actions are bringing pressure to bear on USA agencies to force them to comply with the Constitution. Without those actions, the NSA would continue to run wild as a rogue agency.
I think the only sane way to resolve this mess is to let it alone until Obama's last day in office. Then give Snowden the same kind of Presidential pardon that President Ford gave to President Nixon: a pardon before trial, a pardon before even accusation or indictment. Let Snowden have his passport back, so he could live and move anywhere in the world with the same freedom that any other USA citizen enjoys. But make it clear that he is not welcome to return to the USA, since nothing good could come of that. I would even support paying him a modest annuity on condition that he never return to the USA, and never take any further legal or public action regarding his status. Let him live out his days as, in the view of some persons, a reprehensible outcast in exile. And in the view of other persons, as a patriotic hero whose sacrifices include ostracism from his native land. Let the historians of a hundred years from now be the ones to measure the value of his actions. There is no reason why that has to be done now and there are many reasons why it should not be attempted until all of us are dead.