Earlier quoted context omitted.
I tried searching for the charges that the US brought against Snowden and then the penalty for those charges. According to Yahoo[1] (which isn't a great source but it is the best I could find in the short time I have), the charges brought carry a max of 30 years in prison, along with fines. That is a whole lot more than just 2 years. On top of that, you can bet that US government is going to go for broke on that case…
Max sentence is unlikely. Libby and Kiriakou both got 30 months and they exposed covert agents which Snowden did not (I know Libby served no time, but he was still sentenced). If Snowden is brought home to face charges, he will probably get a worse sentence now because he fled.
You really assume that Obama would commute Snowden's sentence? Really?