A few people have guessed that they may be setting up Kim to show up at the Cinnabon in a future flash forward scene (she is from a small town on the Omaha/Nebraska border, etc).

However, I think the twist won't be that she shows up. It'll be who she is with....none other than one Howard Hamlin, her now husband. Imagine that it will start with the kids at the counter ordering something, then Kim will come up, not recognizing Jimmy. Jimmy will be obviously shaken, but nothing an oblivious consumer will notice. But then her husband will come from out of frame to help with the kids.....it's Howard. Jimmy will barely be able to hold it together as he gets someone else to finish their order.