Yeah, three years, at $5M-6M per is a very reasonable contract for Haynesworth. But it's short, and there's no way you keep him longer that that on the deal. You also can't franchise him, since the contract makes him get cut. Still, Suh and McCoy are such top prospects that I can't imagine anyone deciding to go with Haynesworth instead, so as far as shaking up the draft, I think it's unlikely.
Needless to say, if he won't play 3-4 in DC, he won't play it here.