It isn't too strong a word considering he's the only realistic deep threat on the team. Lose him, and the entire field becomes compressed for the defense.
Not having a safety on permanent deep duty would go a long way into blunting everything else the team is doing on offense.
Trade value? If everyone accepts your premise that he's disgruntled, almost zero trade value. Just wait for the contract to expire or for the Saints to release him. If they wanted to trade to get in front of the line ... maybe a second or a third with an average rotational player thrown in? I feel most teams would want to take their chances in the draft with a first. No need to go crazy trying to acquire someone the team is never going to successfully resign.
Edit: looks like I'm catching some blowback. I think the entire premise is asinine. I was just going along with what I think other teams would be thinking if the Saints tried to deal a disgruntled player. Summary: why trade now for someone you think will end up on the free market anyway?