Annapurna, the banner run by Megan Ellison, will finance and produce the social satire, making the long-in-development project an actual reality, with an eye towards an early 2016 production start, THR has confirmed.
Matt Damon and Reese Witherspoon are attached to star in the story of a man, down on his luck, who decides he can have a better life if he undergoes a process to shrink himself.
Ellison will now join Payne, Jim Taylor and Jim Burke as producers on Downsizing.
Baldwin is currently shooting Mission: Impossible 5, while Harris last appeared in Gone Girl and A Million Ways to Die in the West. Sudeikis last starred in Horrible Bosses 2.