I'm hoping it'll be Enzo, of course. But I think it'll be Sami, the WWE would be stupid not to cash in on how stupidly over he is at the moment. I'd love to see Kruger with it though, he is absolutely awesome. He's the most ready out of all of them for a call up IMO.
The obvious choice is Sami. Unless he gets a call-up. I'm not entirely sure there's a place for him there, yet. It's still too crazy with the current storylines on Raw/Smackdown. It makes sense to take your NXT rookie from Montreal to Canada, and your Arabic speaking NXT rookie to Abu Dhabi. But whether this will manifest into a full-scale call-up isn't clear yet.
But if he does get a call-up, I'm willing to guess that Graves will have a brief, bland reign. Or maybe Ohno, if he's gotten himself back in the office's good graces. Apparently they still think very highly of him except for his love handles.