So here's a thing, which hinges on Catherine Keener's presence in both Being John Malkovich and Get Out:

[In Being John Malkovich] After becoming pregnant by the body of John Malkovich while Lotte was inhabiting it (I probably should have mentioned that this article is NSFW), Maxine [Keener] gives birth to a daughter, Emily, whom she and Lotte happily intend to raise together. Except, as we learn in the last scene of the movie, Craig’s soul is actually trapped in the young daughter’s body. Talk about a classic setup for a sequel!

As the theory (which likely began on Reddit but has now become widespread enough to warrant its own lengthy section on the Being John Malkovich Wikipedia page) goes, Maxine and Lotte continued to crave the experience of inhabiting other people’s bodies, even after the Malkovich portal had closed. They eventually crossed paths with neurosurgeon Roman Armitage, the malevolent patriarch of Get Out, who transplanted the spirit of dressed-down Cameron Diaz into the body of Bradley Whitford (Malkovichy enough, I guess, given the options). Of course when you relocate your family to try and find illicit portals into other people’s consciousness, it’s always wise to assign everybody new identities, so “Rose Armitage” is actually grown-up Emily, and such is the nuance of Allison Williams’s performance that I didn’t even realize she was playing a disgruntled John Cusack trapped in a young woman’s body until at least the third viewing.

[...]

Still on the fence? What if I told you that the place where Chris finds the incriminating photos of Rose’s past paramours in Get Out is … BEHIND A VERY TINY DOOR? (Source)

Jordan Peele was asked about this theory and apparently likes it so much that he's decided it is true.

Big thanks to Tim!