With Survivor Series in Atlanta it makes sense for Sting to hold the World Title at least till then, actually PAST then, losing shortly thereafter.
WWE seems to have no interest in a Sheamus Title Run and he's been mostly on the lower half of the card all year anyway, not exactly a great place to be if you're on the verge of a World Title Win unless you're a big time established legend (which he definitely is not).
Rollins should lose both titles at NOC - It validates the importance of what is otherwise a "throw away" PPV, plus it's the first real set back for The Authority all year - W-Mania was a 4 hour show dedicated solely to putting over The Authority as the best Heel faction and most powerful force in wrestling today and it worked, it's time they lose a few to even the score with the rest of the crowd before they get so boring no one cares (or as I Like To Call It "NWO Syndrome").
All the best heel factions stay relevant by losing power periodically, giving the fans what they want to see (bad guys losing), then re energize storylines by going back on the hunt instead of being the hunted all the time. The Authority is due for a fall, and if WWE has value in Sting, especially with the mega W-Mania in Dallas he needs a significant victory. He is also the only character on the show who hasn't been handled thoroughly by The Authority, including Cena, so he is the logical one to "knock them down a peg".
Plus, are there any match ups worth more money with casual fans than Sting-Taker & Sting-Lesnar, which would have added appeal if Sting was WHC ?
I say let Rollins lose both titles, he wrestles a great match vs Cena, loses, then attacks him post match and is injured in the ensuing brawl, making him slim pickings for Sting but let him still have a good match vs Sting, play up the injury angle to show his toughness, which has been questioned, but let him be competitive in a clean, decisive loss.
This sets up all sorts of storyline potential with A) heat between Rollins & The Authority for losing B) The Authority's Quest to take out Sting and regain the title C) Return Lesnar to the mix and have a legit full fledged fued with Rollins/Authority over who should get the title shot (this could fill some time while Sting ISNT wrestling since his limited dates and age likely mean he isn't taking a full time schedule) D) Start a major fued over The US Title with Cena headlining house shows (you wont get many house shows out of Lesnar or Sting) E) Allow Sting his "Homecoming" to Atlanta for S-Series (The home base of WCW) and let him be victorious, in a grueling match, setting him up to lose the title shortly thereafter - Sting disappears for awhile then returns for one last match at Mania