I can't imagine Decker will leave. Somewhere down deep he has to understand that he is not the same receiver if Dalton or Tannehill (etc) are throwing him the ball. It's a two way street. Any receiver who would walk away from Peyton is an idiot.
I'm putting pass rush (again) and DB at the top of the list this year. Trent Murphy, DE, Stanford would be a good first pick. He's a very disruptive, high effort player. Some are now questioning his "explosiveness."
He led the nation in sacks. I prefer the record on the field than the one in the gym. Frankly, I wouldn't be surprised to see the Broncos trade Von. His long term reliability is suspect and the Broncos have proved they can do fine without him. Another Pac12 player to look at is Shayne Skov, ILB, Stanford. He's another high effort player who could really help out stuffing the run. Gilbert would also be a solid addition at CB. He's made his name making big plays. Always a good deal to improve the INT numbers.