Personally, I hope neither one of them happen. I have no desire to see The Rock become WWE Champion again because, as many have stated in numerous posts on this subject, he's not going to stay around. According to Forbes, The Rock is the 5th or 6th highest paid movie star in Hollywood right now. In the past year, he's made nearly $40 million doing his thing and his price will probably only go up if his movies continue to do well at the box office. If I'm not mistaken, Rock is currently filming yet another movie and probably has another lined up after that. Punk's been working his ass off as WWE Champion for almost 8 months now, so having Rock just show up and take the title from him at SummerSlam would be a big slap in the face in my eyes. I know he's The Rock but The Rock isn't someone that's going to help carry the company for the next decade or so. Frankly, Punk deserves much better than to drop the title to Dwayne Johnson simply because he's The Rock, even if it's just a very brief run.
As for Cena possibly cashing in MITB on The Rock if he did win at SummerSlam, it'll never happen. John Cena is the ultimate babyface and the ultimate babyface doesn't stoop to the low act of cashing in on an opponent after they're worn out & exhausted from his match. Cena will cash in MITB in the open and challenge the champ in a straight up match, which is the way to go this time because it hasn't been done since RVD did it back in 2005. We've seen so many surprise cash ins that the idea of a wrestler doing the noble thing and challenging fair & square is actually a novel & interesting one.
The Rock's message about still wanting to be WWE Champion again does give me concern for Punk's title run. It's all but written in the stars that John Cena will win the WWE Championship MITB match. What I think is more likely to happen is that Cena will eventually cash in on CM Punk and regain the title with The Rock ultimately challenging Cena to a rematch at WrestleMania 29 for the title. There've been rumors about a potential WM rematch between them really since WM ended. I'm just hoping WWE doesn't go down this route and include the title because it'll still give away the ending of the match just as it would have at WM 28. Like I said earlier, The Rock isn't giving up being a movie star, which means he can't be a viable WWE Champion, which further means that having him challege for the title can only realistically end with him failing to win it and thus obliterating any mystique surrounding the match.
In my opinion, Cena winning MITB and successfully cashing it in is a waste of the concept. Cena is already bigger than MITB and doesn't need the gimmick to be a legit challenger for the title. He's John Cena after all, he's the WWE's golden boy and has been the face of the company since the mid 2000s. Cena is someone that, if WWE wanted to, they could just have him come out to cut a promo and challenge Punk for the title and the challenge would automatically have creedence and legitimacy. A challenge can't get anymore legit than it does coming from a 12 time World Champion. Personally, it's a much more interesting idea for John Cena to be the first MITB briefcase holder to unsuccessfully cash in the contract. They've mentioned that Cena has done just about everything except be Mr. MITB, so it'd be a fun sense of irony to have someone as successful as Cena be the first MITB winner to not win the championship. It won't hurt Cena's career one bit if that happens and it could restore a certain sense of unpredictability to the concept in that if John Cena loses as MITB winner, then anybody can lose.
