Sources
Not quite the romantic result everyone had been speculating on, but W. Mark Felt was Deep Throat, dobbing in Nixon for mundanely venal reasons.

There’s an argument to be made that Nixon’s resignation had no positive net effect nationally. The war didn’t end sooner and political dirty tricks are still the order of the day. Even before he’d died, however, Nixon’s legacy was subject to revision, glowing colors added to enhance his economic performance as well as his efforts in the Middle East. And there’s always China: only Nixon could go to China. But we shouldn’t forget Watergate, and the impeachment, or Salvador Allende, or Cambodia and Laos, and Vietnam, too, even if it wasn’t Nixon who got us in there in the first place. Much of contemporary American society has been harmed to one degree or another by Nixon’s own policies and actions, as well as those his administration fostered around the country and around the world.

So even though Mr. Felt didn’t get the promotion he deserved, he did the U.S. a service and deserves thanks.