According to reports from this week's Tribute to the Troops special, current World Heavyweight Champion John Cena did not come to the ring with either his title, or the WWE Championship for his scheduled match. While this could be a possible spoiler for this weekend's big unification match, Cena's presence at Tribute to the Troops was more of a run-in, where he made the save for other babyfaces, and was then booked in a 6-man tag match.
The special will not air until after this Sunday's WWE TLC pay-per-view leading many to believe that WWE didn't want to upset their continuity should Randy Orton be crowned the Unified Champion. Generally the Tribute to the Troops special is a separate event that doesn't affect the weekly programming on Raw or Smackdown, so it's likely that by not having Cena appear with his title WWE was just protecting either outcome at the TLC pay-per-view. Plans can change on the fly and it is possible that the WWE creative heads are still working on the finish to that match, rendering all "potential spoilers" as pure speculation.