It's only greed (concerning both sides) that is stopping it from happening.

Earlier in the year it was Mayweather who was demanding too much in the form of a 60/40 split. Now Pacquiao's camp is not only expecting the 60/40, but also wanting a ridiculous catch weight (again).
If I were Manny or Floyd I would push for the fight be at 146 with 50/50 split or winner-take-all... but alas, I'm just a fan who wants the corruption and politics in boxing to dissipate.. (I don't think that'll happen any time soon )