I actually mentioned something similar to this before Cena became champ again. I was speculating on who his opponents could be throughout the year since it was hard to think of many fresh ones for him, and one idea I came up with was throwing a mid carder/upper-mid carder in there with him for one PPV just to give that person a bit of a rub and see how well they do and how people react to them in that spot. The company has done this from time to time in the past and Daniel Bryan fits that position perfectly at the moment.
Because of that though, I don't see Bryan walking out as champ. Him winning the title right now would be him climbing to the top way too early IMO. How long has it been since we've seen someone's chase and journey to win the world title for the first time? Bryan has never been WWE Champ and him coming THAT close to winning the gold only for it to slip away from him is a great story, and will only make people want to see him win it that much more when the time finally comes. It's a great way to continue the story of a guy fighting hard to prove he deserves to be treated with the same diligent and respect as his peers.
I also think the match is meant to benefit Cena from WWE's point of view, as they clearly want to make this current title reign his most legendary yet given that he defeated The Rock (his biggest opponent to date) to get it, which wrapped up a story line that ran two years and three Wrestlemanias. First, it's feeding him a brand new opponent he hasn't yet faced and overcome in Ryback. Reports also say they want Cena to have a big legendary moment by performing in a Three Stages Of Hell match. Daniel Bryan coming next could be the company's way of getting a five star pure wrestling classic out of Cena. Bryan is the perfect guy to do that with.
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