As much as the festival seemed like a set up for a big event that would grab attention and set up some kind of later plot point, maybe it would be better if it just ends on a normal note, then the next morning everyone goes back to business as usual? Creating our own missions would be much easier than trying to do any kind of major plot and then the impetus would just be on completing those for a bit, maybe until Vongola gets back or someone gets better ideas.