Actually that studio you mention as DNA is Tonic, their full name is Tonic DNA. No, the fourth studio is Yearim, who already animated on Wabbit.TVTropes says that Tonic, Snipple, DNA, and Yowza are doing the animation. Surprisingly one of thems actually in the United States...though DNA seems to just be a small studio that works in 3D, so they'll be animating the background Unity assets.
I never did understand why the States can animate 3D or even occasionally stop-motion work, but any 2D work gets sent over seas. I get that some of this is to do with theatrical animation vs TV animation schedules.