Good scenario, though OTL the Watergate break-in itself didn't occur until June of 1972, so if by "break" you mean "be broken by the media", there won't be anything to break in early '71. If you mean some other wrongdoing by Nixon gets exposed in '71, that could be plausible, but I don't know if anything would capture the public imagination quite like a break-in.
If it somehow got revealed that Nixon stalled Vietnam in '68, that could have some serious ramifications. A break-in and cover-up is one thing, but actual treason is another.