I think WWE would make a strong move to keep Owens. Unlike a lot of Hunter's indie signings and NXT callups, Vince has always seemed to like Owens. He has always been pushed and featured prominently. Vince took shoot headbutts at a million years of age to get Owens over. He also got numerous visual victories over Roman in their feud this year, which indicates that they want to protect him.
With Sami, I don't think WWE tries that hard. He is certainly stale and overexposed, but he has the advantage where he can just put on his mask again and instantly change his look. El Generico has never worked for WWE after all.