It really just depends on what Devon shows up. If he comes in with the gameplan of stepping in with his shots and checking Khan's chin regardless of how pretty it looks, then he'll win because there's no way Khan will be able to dodge his quick hands all night and even though Devon's not a great puncher by any stretch, he's probably got enough pop to check Khan's weak chin. If he goes in with the mentality that he's going to outskill and outbox Khan, Khan has a good chance with his length and speed. There would still be the danger of Alexander catching him with a big counter but it could turn into Khan vs Judah again in that scenario.
Khan has zero punch resistance. Skill wise I think Khan has a better set but that doesn't even factor into a fight where one the boxers CANNOT take solid shot. Devon will land clean and hard if you think not than you haven't been watching Khan last couple fights. I would be surprised if Amir makes past six.
I dont think the skill sets will matter for either. If Alexander lands a big suprise punch, Amir is going to go to la la land