I'm very happy with the line-up but can't lie that a late add wouldn't be sweet (Was fully expecting Big Boi, Solange, MBV & Toro Y Moi to be playing and seems strange they aren't). Maybe they'll take advantage of the 2 weekend thing by having certain artists that can't commit to both weekends pop up to play one of the weekends. Even though Coachella has no financial incentive to have late adds, it always helps with cred and builds hype for the festival.
Such as when Radiohead secretly added to Glastonbury in 2011 (Which was long sold out)
Kanye last minute added to Coachella in 2006 (Most passes were sold out but was before mandatory 3 day pass)