Mark Felt has long been a leading candidate to be Deep Throat, and I recall once reading somewhere that one of his kids, I think, told another kid at summer camp about 15 years back that his dad was Deep Throat. Ill have to go back and see if I can track this down.
Meanwhile, what if, as popular theory has it, there was more than one W & B source that they called "Deep Throat"? That would complicates matters, because somewhere out there, one of the other persons who think hes Deep Throat (John Sears? Fred Fielding???) will be really pissed off if W & B confirm Felt.