THQ has explained in more detail how the "ring collapsing" gimmick works in WWE '13. Cory Ledesma tweeted that you will need 3 finishers to execute it and all matches end in an instant KO when you use it. The person who wins the match is obviously the person who executed the superplex in he first place.
The Ring Collapse KO is part of the new finishing moves that players can initiate in WWE '13. If you haven't seen the ring collapsing before, the following video will give you an idea what's in-store for you!