At this point, finding some evidence randomly is the best to hope for, IMO. Hopefully (not for the unfortunate hiker who would come across possible remains) someone walking in the park/area will discover him.I don't think a search of that size has ever been conducted by any agency, state, federal or local. At this point, I believe it would be considered a recovery mission, as well. Not sure where all the volunteers would come from.
And since only a tiny fraction of the perimeter of the park is available by a reasonable hike, searchers are limited there too. They'd have to be reprovisioned and all that (just as the original perps would have had to have been).
He can only have wandered so far and if he was abducted, I doubt he was literally carried off - there was a car involved. But I seriously doubt that they've even searched with a 5 mile radius of all roads...it would be an enormous search. 100's of square miles. Weeks and months of volunteer coordination.
Also, his sister Dawne has discussed returning yet again in the fall and has acquired permission to use drones to search for him. Perhaps the drones will spot something more easily than a random passer-by on the ground. I sure hope she has success this time. What a long and painfully drawn-out nightmare for all his family and friends.