#4 On the Road to WrestleMania
As often the case, stars often return in the Royal Rumble match itself (Naomi, Edge) or on the ensuing episodes of RAW (Ruby Riott) or SmackDown after the Rumble. A lot of those returns depend on potential plans/storylines for returning stars and/or the severity of injuries that the stars might have suffered from.
Ruby Riott had been out of action for almost eight months after having surgery on both of her shoulders. She came back to attack Liv Morgan on the RAW after the Rumble, but has yet to have a match.
A WWE Hall of Famer isn't a John Cena fan. More details HERE
Both before and after the 2019 Royal Rumble, stars like Lacey Evans, Nikki Cross, Ricochet and Aleister Black all debuted on the main roster. Black and Ricochet were eventually a part of the SmackDown title match at WrestleMania 35.
If Kross skips NXT, then he could debut after Elimination Chamber or Super Showdown. There are plenty of stars that may be without dance partners at the Show of Shows, so Kross showing up to target someone like Daniel Bryan or Ricochet would be an interesting way to debut. Attacking a beloved face always gets great heat for a debuting heel or for someone turning to the dark side.