It seemed like every 3rd pick in last years draft was a DB. I think all that "inventory" contributed to DK's drop in the draft. Maybe this year, there won't be so many?
If he can do in the top 2 rounds, he has to go. Too much risk to wait.
I think your understanding of the economics of CB drafting is off. Teams weren't drafting a ton of CBs because there was a huge supply. They were drafting because there was a huge demand. DK dropped because his tape in his SR year, measurements and inability to cover top players at the Senior Bowl told teams he was going to have to play safety at the next level.