#3 Sheamus

Sheamus has been out since the SmackDown after WrestleMania, where he suffered a concussion during a tag team match against The New Day. The Bar, the tag team of Sheamus and Cesaro, was split when Cesaro, who is also a singles star now, was moved to RAW.
Sheamus, in a recent interview, didn't reveal much about his WWE future, but said that he wants to return to the ring (IBTimes):
Did Goldberg ruin Bray Wyatt's career? - Watch Now!
"I don’t know what the story is in my future. I have no idea, I honestly don’t. I just know that I like have some time off but I do miss being in the ring."
In the same interview, the former tag team champion said that he will target the Intercontinental title once he's back to SmackDown: "If I get back to the ring, that would be the first thing I would go after. As of now I am still listed as a SmackDown superstar and the title is on SmackDown. But as of now, I have no access to the title but it's definitely the one I want."
Could we perhaps see Sheamus return as a babyface and feud with Shinsuke Nakamura for the Intercontinental title? That will be an interesting feud and one that's needed for both Nakamura and the Intercontinental title currently.
One wrong move ended Big E's career - Watch Here!