Shawn Mendes follows up his hit "Stitches" with a duet with Camila Cabello, "I Know What You Did Last Summer." It nabs a double HitPredictor this week, at Top 40 and Hot AC. Three songs close out the year with a second HitPredictor this week: "Hollow" by Tori Kelly at Rhythmic (following Top 40); "State of My Head" by Shinedown at Alternative (after Active Rock); and "One Call Away" by Charlie Puth at Top 40 (after Hot AC). This is our last HitPredictor newsletter of the year. Happy holidays!