Hillary Clinton is also the leading potential Democratic candidate for 2016 (despite her denials). The other leading figure is Joe Biden. Both are implicated in spreading an account that nobody now believes or even defends.
Think next about the ripple effect when figures of this weight fall under a cloud — if they suddenly have to start hiring lawyers, answering subpoenas, trying to recall when and where they were told what, and eventually resigning and going into private life. The longer Libyagate lasts, the more likely it is to damage the Democrats. It would mean more than merely a lost election (though it might well mean that too). It would mean a wholesale revolution at the top of the Democratic party.
Without Watergate, neither Gerry Ford nor Ronald Reagan would have got near the presidency. Nixon’s successor would have been someone like George H. W. Bush or John Connally. Nixon rather than Reagan would then have shaped the modern Republican party, rather as FDR shaped the pre-Vietnam Democrats. The entire spectrum of American politics would have been different (and conservatives must surely think much worse).