Twitter user TheEvanLambs posted a pair of photos revealing the presence of a steel cage. One photo is from Triple H's Instagram account, showing the mesh somewhat inconspicuously in the background, while the other photo shows the cage hanging above the ring, shrouded by a black tarp.
Of course, the inner conspiracy theorist might surmise that the cage could be a red herring, if Triple H were innocuously tweeting out a photo of it (second photo from his Instagram set at the above link). Then again, why assemble it if it's not going to be used?
The first fall of Gargano and Cole's match will be a street fight, per Gargano's choice. Cole selected a standard one-on-one match for the second fall, while GM William Regal will make the call on the third fall's stipulation, should it (inevitably) come to it.