I don't see much of a problem with this match. Cena at the least has proven that he can pull out a 5 star match, and regardless of the opponent it takes all the competitors of the match to do so.
Alberto Del Rio is decent enough in the ring, personally I do not care too much for his promos, but they have the consistency of character and development to lead to him being in the spot that he is in, defending the WWE title, although I would argue that he should still be in his first reign not his second, but credit to WWE were i believe it is due, they gave the title back to him swiftly, showing that even if backstage support for him is wavering it is there, and there are people that believe he can be a maineventer in WWE.
I do not think that this is the top story currently playing out on RAW, in my opinion would be the CM Punk storyline, although this has been intertwined with that story and very well may be again. It is still not a bad storyline, I do not find it hard to believe that Cena would be more focused on regaining the WWE title that Punk would be, and with Misterio injured obviously he is not looking to regain. Being either challenger or champion is more a part of Cena's character than it is Punk's, who is going along with the change within the WWE story at the moment, but will more than likely regain the title at some point in the not too distant future.
I am expecting Del Rio to win this match, and hopefully a win will make him seem more of a credible main eventer and champion. in my honest opinion, whether including interference or not, I think the best finish to this match would be to have Cena tap out to Del Rio's cross arm breaker. This would seriously help Del Rio be viewed as a true maineventer and credible champion, and can be done without a great deal of damage to Cena's character. To the best of my knowledge Cena has never tapped out in a WWE ring, and with the upcoming Wrestlemania match with The Rock and high possibility of teaming with him at Survivor Series I actually believe that Vengeance would be the best time in his Career to have Cena tap out. Show him in a true situation were he is in the middle of the ring, the submission is properly and expertly applied, and Cena is faced with the choice of holding on and risking his arm being broken, and thus the cancelation of his Wrestlemania match with The Rock, or at that one and just one precise second of his entire WWE career, deciding that the best option is to tap and save the Wrestlemania match.
It would not be something to be ignored, and I think if such a thing were to happen Cena should bring it up at the next RAW. If must be he can apologise to the fans for tapping, and say that he did so for the fans, because he knows that Cena vs Rock is a big match, and he did not want to risk it not happening for both his and Rocks fans. The biggest problem of this outcome, the fact that Cena would have tapped and so has been shown as able to be made to submit, could easily be confronted by having Cena vow to never again give in during a match, and at some point, maybe several, have The Rock place Cena in a Sharpshooter and show Cena either escaping time after time, or simply refusing to submit Stone Cold Steve Austin style, not so much recreating the storyline, but referencing the Bret Hart, SCSA match to any fans that have seen or are aware of it, and relying the same determination to not give up.
Thus in the long run we end up with a John Cena who is arguably more determined than ever, and an Alberto Del Rio who is still champion, and hopefully more credible, who is now able to go on and feud with other main event talent within WWE, whether that be CM Punk, getting involved in the power struggle storyline, Big Show (who I am actually shocked to find is actually officially on the Raw roster) or maybe a return to the ring by HHH.
In the long run I think this main event actually has the potential to be the point that sets up the main RAW storylines for the upcoming months, maybe even until Wrestlemania, by helping to put the characters in the match, and those associated with the story into the mind frame and setting that will lead them into 'Mania's card.
If Cena is to win I am honestly not sure where the storyline may go, Cena yet again is WWE champion, and Del Rio would have another short title reign. Besides the obvious rematch I see Miz and Punk as the obvious choices of next challenger, with Miz portraying a top heel and Punk a face character that could quite easily Conceivably compete for the title against an also face Cena.
So I am expecting a Del Rio victory, but if that does not happen I can at least see possible storylines than can be put in place for a champion Cena.