Were Woodward and Bernstein solely responsible for revealing Nixon's involvement in the Watergate cover-up? Or was the cover-up unravelling of its own accord anyway?

If I remember correctly from the duos book, the New York Times were also doing their own parallel investigation and did reveal parts Woodward and Bernstein had no information about on a few occasions.

I think the duo was instrumental to get the official investigation going by digging deeper behind the Watergate burglars. The story may have ended with the trials of the burglars. And then I also think they were instrumental in getting the investigation going again after the first level of trials of the men behind the burglars, hence pointing or driving the official investigation in the direction of the White House and the president.