#3 Robert Roode
Robert Roode has been off TV since shows started to emanate from the WWE Performance Center. He has also been left out of the ongoing Mandy Rose/Ziggler/Otis/Sonya Deville storyline also, probably due to travel restrictions brought on by COVID-19.
The Glorious One is in phenomenal shape and is a great mid-card heel whether working alongside Ziggler or otherwise. The tag team was thrown together rather randomly but was still a pairing that worked. They were a big part of the King Corbin vs. Roman Reigns feud but were mainly used as minions for Reigns to battle until he got his hands on the King.
A lot of stars have competed in at least one MITB match and Roode has exactly one match under his belt (in 2018). That year, Braun Strowman hauled down the briefcase. Roode could still fill a spot and he might be in a qualifying match to earn a spot at the PPV, however, his time as a potential main-event guy has passed.
So despite being a heel while the WWE Champion is a face, the former US Champion should be left out. He's still great at being a heel but doesn't draw the ire of the crowd as much as Sheamus or King Corbin. Someone like King Corbin, although generally loathed by the WWE Universe, is better suited to getting another shot at a briefcase and a run at the top dogs of SmackDown.