Never happen. Holder wasn't held accountable by the Bush Administration or the DoJ for his role in the Marc Rich last-minute pardon under the Clinton Administration. He ain't gonna be held accountable for this either. Republican's don't have the testicular fortitude to do it.
Note: I would be ECSTATIC to be proven wrong on this point, sadly I know I won't.
It has nothing to do with testicular fortitude and everything to do with media. Republicans that stood up for constitutional principles have been destroyed by the MSM, repeatedly over the last few decades. Now there is enough new media, and the MSM has lost enough credibility, that they can be destroyed from two fronts: the MSM and the new media.
Now even relatively minor scandals that would have brought down a Republican, but never have bothered a Democrat, can bring down Democrats, such as Weiner in the twitter scandal. Republicans such as Lugar have shown that conventional appeasement of the MSM is not a safe harbor.
Old Republicans have to fear both the MSM and the new media, so they are caught between a rock and a hard place.
Democrats have only the new media to fear, but they feared nothing before.
We have been transitioning into a new age since 1994.