Another thing the MITB winner could do is to change the shape of a card. For example, for Summerslam we had Cena vs Corbin and Nakamura vs Mahal for the championship. If Corbin had succeded cashing-in, then Corbin vs Cena would have become the title match and Nakamura vs Mahal would turn into a non-title match.
Another angle is something similiar to Prometheus stealing the fire of the gods. On RAW, you have a heel authority figure. That authority figure, after certain events, bans a face wrestler and fires him from RAW. Let's say, Seth Rollins for example. Rollins goes to Smackdown, because he has nowhere else to go. MITB comes up (now a dual-branded event, like it should be) and Rollins wins the MITB match! Then, instead of Rollins cashing in on the SD world champ he cashes in on the RAW world champ and steals the belt as an act of revenge. This is like the CM Punk angle but done between RAW and SD. Rollins takes the belt to SD and defends it there. This could lead to a big RAW vs SD match at Survivor Series.
To take this even further, Vince comes back to solve things. Vince fires the heel authority and takes the champion back on RAW. The heel authority returns, with a heel stable and injures the champion, taking him out of action and thus vacating the title. This group is something like NWO, but badder. They come from the outside and want to take revenge on Vince McMahon and Seth Rollins. The heel leader wins the vacated championship, Rollins returns from the kayfabe injury and challenges him on Wrestlemania.