The last time that the United States Heavyweight Championship was defended was back in October, when Dean Ambrose successfully defended the title against Big E Langston at Hell in a Cell 2013 and on Monday Night Raw the following night.
While he has not been given a feud to work with since making his return to WWE, Rey Mysterio is very much still a part of the plans for Wrestlemania 30. He was penciled in for a big match against Sin Cara, but management is now looking for a new opponent for him at the pay per view.
Aside from half hearted programs with Sin Cara and Rey Mysterio, Alberto Del Rio really has not been given a full program by WWE to work with since wrestling John Cena at Survivor Series 2013. However, the feeling backstage is that Del Rio is assured a spot at Wrestlemania 30 to draw in the Spanish media.