Plus, I don't get the obsession with drafting a LT.
First, Humphries is only 30 year old. He still has 4-5 years left. OT's can play later in years. Hell, Trent Williams is about the best LT in the league and he's 35. Andrew Whitworth was 40 and the starting LT on a Super Bowl winner.
Second, you used a top pick on Paris Johnson last year. He wasn't drafted to be a RT. He's played well but RT's aren't drafted in the top 10. Especially trading back up to get him.
Drafting Alt or Fashanu doesn't make the Cardinals a better team. They are not going to be as good as DJ. I don't know why the Cardinals would want to move on from DJ. But, if they do, slide PJJ over and get a RT in free agency or draft one later in the draft.