Perhaps its just pessimism but there likely never be a pardon for Snowden. Once and if Snowden is pardoned, the military has now made it "acceptable" to comprimise secrets. Though Snowden is arguably in the moral right, if someone does this sort of thing for poor/naive reasons and if the knowledge is more sensitive (such as Hiraldo Rivera explaining exact locations and plans on a broadcast) there may be a much bigger problem.

I think the closest Snowden will likely get is an honorable burial in US or have a bill named after him. But I highly doubt either party will pardon him.