HIGHLY Doubt its Trips or HBK
From my online reading, HBK is enjoying retirement at the moment, and Triple H is either recovering from a Neck injury or he's filming a movie (or both) but the fact that Shaemus has the belt tells me most likely that Triple H will be back soon as Ive also been reading that Shaemus would get the title again and it would eventually lead to Triple H vs Shaemus and Triple H would win the title again.
Jim Ross- A possibility but from my reading hes enjoying being behind the scenes, but at the same time that's who I am suspecting too unless they got Vince Russo heh or maybe its a McMahon but I doubt that too