Only if their discrepencies occurred under oath. It remains to be seen how it will play out in court, but my original point was that Woodward's admission of his knowledge does not change in any way Libby's alleged discrepencies about his conversations with Russert, Miller or Cooper. I think the central point will probably be that White House documents contradict his claim of uncertainty about Plame's status. Now, if Libby had been actually charged with outing her, then, yes, Woodward's testimony would have collapsed the case.
"It remains to be seen how it will play out in court"
Unfortunately it won't play in or out of court. The charges against Libby will be quietly dropped with some solemn pronouncements of compassion, costs, and the public interest. Woodward has effectively seen to that.
Which is too bad. It would have been fascinating to see Our Man In Nigeria, the Hon. Jos.Wilson, and his various elves, under both oath and the thumbscrews of Libby's defense team.
Rocks would be overturned - many creepy-crawlies exposed to sunlight. Can't have that happen. Ol' Woody just took one for the team.