Good, because Tet essentially spelled the end of the Vietcong. The U.S. was initially caught off guard, but regrouped and crushed the Vietcong to the point that they were never again as effective as they previously were.
Charlie just waited until Congress/LBJ sold out our military and then marched into Saigon. Charlie capitalized on our true weakness that was revealed by Tet: a weak, worn out, ignorant President and a chaotic, poorly led Congress.