It's all up in the air, I think.
Duffy seems now determined to drag Harper down with him, but Duff is now pretty much classed in that layer of scum just above pedophiles in the public mind, so his word may not be taken for much. The people who already have a dim view of Harper have already assumed that he knew all about it (and to be fair, given his character, the alternative seems pretty hard to imagine), so that won't change their attitude. It'll take something far more explosive than what Duff and Wallin went on about today to really start to crack that shell. Though it's not impossible that Duff could hammer away at this in an attempt to convince people that Harper is "as bad as he is", but he doesn't seem smart enough to play that angle.
There are of course the unknown unknowns, to quote Rumsfeld. The biggest one being the rumbling chance of a caucus revolt amongst the Conservatives, but I think dear leader's iron control is still more or less intact for now, in spite of the dings he's gotten. "The man who brings victory in battle is prized above all others" and all that (Apologies to Anthony Quinn).
If anything, every day of this spectacle reinforces the broad desire for the Senate to be completely abolished.
EDIT: Also in regards to a potential caucus revolt: While it's becoming ever-more inescapable that Harper will cut anyone at any time, that is actually old news. The Harper caucus is still dumb enough to let each other hang separately, still rationalizing "It won't happen to me. I'm loyal!" That's the real fallacy Duff needs to target if he really wants to hurt Harper.
