Listened to the Anthony Pettis interview on MMA Hour and Dana hasn't returned his text regarding the fight with Aldo. That suggests to me that Showtime will have to wait his turn at the LW belt, which means Lamas is probably #1 in line for Aldo.
Regarding title shots, the UFC business model depends on having "highly anticipated" title fight headliners for every (or nearly every) fight card. But the natural order of randomness** doesn't always carve up a single clear cut contender for every weight division every 3-4 months, and thus, Zuffa often find themselves trying to fit a square peg into a round hole. If they have to force an option to fit, I prefer that option comes off an exciting win (Weidman, Showtime) as opposed to a suspension (Diaz) or a loss in which the challenger got finished (Sonnen). Just the lesser of two evils.
**That randomness is what makes the sport so damn exciting, as seen this past Saturday night at UFC 156.