#1 A title change
The United States title hasn't exactly been the most prestigious one over the last few years. When looking back at it from 2017-2019, it's incredible as to how many title changes there have been. From transitional reigns to title changes simply for the sake of having title changes - the title hasn't been treated with the same prestige that it was when John Cena held it over four years ago.
AJ Styles had a great reign as the United States Champion this year, having the only lengthy reign with the title. Mysterio was the right name to dethrone him because the match after Survivor Series was a hot one, with the legend having momentum following the Brock Lesnar match.
Seth Rollins would be the perfect name to dethrone Mysterio and though we're not a fan of short title reign, it would make storyline sense for Rollins to dethrone Mysterio, especially since he has the numbers advantage at ringside with AoP being there to assist him.