It's starting to become a yearly tradition to have a rumor that WWE's bringing back MITB at this year's Mania. It's not going to happen, they have an entire PPV centered around it that takes place just three months after Mania. People can bring up the HIAC match last year as possible defense but their was a much a larger gap in time between Mania and the next HIAC PPV, and a HIAC match has no ramifications going forward. A Money In The Bank match does, and do you really think WWE has three people the see as next break-out stars. Also, it seems suspicious that the returning of a MITB match to Mania comes as a side note to Ryback news. Like I said, MITB won't happen at Mania this year, and I doubt it would until the World titles are unified and even then I doubt it.
Also, I wouldn't want it to. Let's take a look at the card that was reported awhile back ago; Rock vs. Cena; Brock vs. Trips; Taker vs. Punk; & Orton vs. Sheamus. These were much bigger matches than what the card the last Mania's with MITB's gave us. How much time would you imagine it get? The last few at Mania sucked for a reason (granted, it was more than just time management but still). Besides having three Briefcase winners crowned in the span of three months, let alone one year, is serious overkill. MITB holds the biggest reward of any match, there shouldn't be additional chances throughout the year to win it as it just ruins the match.
Ryback vs. Show is undoubtedly a meh idea. Can't imagine anything besides the image of Ryback shell-shocking Show being anything close to entertaining, but I wouldn't mind seeing that image.