If Obama finally does decide to jettison Holder, he can dust off Nixon's speech of April 30, 1973, announcing the resignation of Haldeman and Ehrlichman, "two of the finest public servants I have been privileged to know" (or something very similar).
If Holder does go, it will be further grist for the MSM theme that opposition to Obama is all about race. Conservatives just want Holder out because he's black, not because he's incompetent, dishonest, racist, and hyperpartisan.
Honestly the replacement doesn’t matter. All the hydra’s heads are the same.