I speculate this will play out like this:
Rummy quits - no need for him to come testify before Congress because he's not in a position to do anything.  He'd be deemed to make a lousy witness anyway because he's so daffy when he answers questions.  And, he'd likely claim bad memory which couldn't be remedied by referring to documents because, now that he's out of office, he has no access to them.

Nomination of successor to follow within minutes, or days, but to be brought up during the lame duck session.  This will preclude effective hearings before the Senate, and preclude hearings before the possibility of Senate changing control in six or eight weeks.  Bushie and his will argue it would be irresponsible to delay, given that we are at war, and equally irresponsible to not confirm his choice because he has the preznit's confidence.

Who will be the successor?  Lieberman is my first choice.  That will preclude the Dems from taking control of the Senate because it will be split 50-50, allowing Deadeye to control everything there.  Rell will nominate a stalwart Repug for the slot - think poor Nancy Johnson or, in the event of a recount loss, Simmons.  
Moreover, by restacking the deck that way, the Repugs can play the "qualifications of the members" game with Webb and Tester, when they win.

I'd suspect Lieberman getting the job and thereby facilitating an (R) in his seat was the quid for the pro quo of all that Repug support through the campaign.

While Addington is an outside choice, I get the feeling he's got too many questions to answer for torture, to get over that easily.  Plus, he's too transparently Cheney's man and has no senior executive experience.  

Not that that matters to this crowd.

Meta-lying.

Though he admitted the election results were "a thumping".  Over and over.

In it he says of Rumsfeld:

One area of neoconservative thought that needs urgent reconsideration is the revolution in military strategy that our neocon hero, Secretary of Defense Donald Rumsfeld, has championed. This love affair with technology has left our armed forces short on troops and resources, just as our execrable intelligence in Iraq seems traceable, at least in part, to the reliance on machines rather than humans. Our forte is political ideas, not physics or mechanics. We may have seized on a technological fix to spare ourselves the hard slog of fighting for higher defense budgets. Let's now take up the burden of campaigning for a military force that is large enough and sufficiently well provisioned--however "redundant"--to assure that we will never again get stretched so thin. Let the wonder weapons be the icing on the cake.

Muravchik's memo opens with this statement: "Neoconservatives have the president's ear, but they also have lots of baggage. To stay relevant, they must admit mistakes, embrace public diplomacy, and start making the case for bombing Iran."

Is TailRunner Joe the replacement? To do that he would cost the Dems the Senate. Would Joe hurt the Dems like that? Stupid question. Of course he would.

May we never see another neo-con again. Except in the Hague of course.