#2. Getting squashed by The Fiend
John Cena is one of the rare top stars in WWE history who has been as unselfish as one can be in the later stage of his career, putting over numerous stars such as Kevin Owens, Shinsuke Nakamura, AJ Styles, etc. while also making Superstars look great in defeat.
In 2017, his record-tieing 16th World Championship reign ended in a matter of two weeks after Bray Wyatt took him out of the Elimination Chamber. Two days later, he would put Wyatt over in a Triple Threat Match for the WWE Champion also involving AJ Styles. In this case, he took the pin and was heard whispering "You're a real champion now" to Wyatt as the match finished.
Many felt that it was wrong for him to beat Wyatt at WrestleMania 30, but there's a high possibility that WWE will use the opportunity to have Wyatt squash Cena the way he did to Finn Balor and quite a few others.
Cena would happily take the fall, but it would be a stunning move to get squashed rather than have an even match.