Keyframing what collection an empty instances

Hello, I'm looking into using 2.8 as a substitute or replacement to Flash/Animate CC, and one of the things that doesn't translate well for what I animate are symbols (Blender equivalent being collections), as I use them for different body directions or hand poses. As blender doesn't have a concept of per-frame objects, being able to keyframe what collection an empty is instancing would do wonders for stop-motion animation while also being an easy solution.