It could happen. Booger McFarland was drafted at #15 in the 1999 draft with Marinelli as the D-line coach. They already had Sapp at their 3 tech. I don't think they would be interested in a big, fat, slow slug 1-tech, but if there is a dynamic, quick twitch guy in the 300-320 pound range I think they would pull the trigger. Not only could he start next to Crawford, but he could slide over at times to give Crawford a blow and be insurance in case Crawford comes back slowly from surgery. Rotater Cuff surgery is a pretty big deal. He won't be able to lift for a few months.
I could see a trade down and then take Billings, Robinson, or Rankins.
The #34 spot won't get those top guys but a few others like Austin Johnson, Kenny Clark, Vernon Butler, or even Sheldon Day, could be available and will be studs compared to Hayden.