Well, there's a scene of Wyldstyle & Unikitty at a dance off at Cloud Strife Cuckooland, and Emmet doesn't have the piece of resistance on, so this could be the epilouge. Either Business sent down the Duplo aliens to destroy them (That's an obvious answer, since Finn's dad suggested that Finn's sister would play with them.) or maybe Lego is trying to hide spoilers.