Since we're getting to see Mia's birth in the next episode, I'm guessing that unless the timeline somehow changes it isn't happening next season and will happen sometime over the summer? Then - unless the timeline somehow changes, Felicity's just off with a baby in a cabin in the woods and no one remembers that chunk of time she wasn't around? Or maybe they're just showing the timeline as it is now and when COIE rolls around they reset the future and Mia is born soon after and we see that the future has been changed?