Impeachment won't go anywhere, he can hide behind sycophants who would twist the whole endeavor as being racially oriented. Even now that one issue is what keeps many mouths silent, on the NSA, Syria, and other events. Go read some of the stories of some of Hollywood's best known anti-war activist are stymied by this prospect.
No, the way to get the message across is to keep it alive and use in the 2014 elections to ensure his party is trounced. Yes that will mean giving the Republican's the upper hand in Congress but fortunately or unfortunately depending on your political stance they are pretty inept at using it well. There are some Republicans that need to go as well and they should not be given free pass.
It comes down to getting the American people to stay interested enough, to adopt the philosophy of "throw the bums out". If that means we swing back and forth each two years or four then so be it, for when one party has dominance too long we get into situations like we are today.