#3 Nia Jax
Nia Jax had battled Ronda Rousey in a RAW Women's Championship match at TLC but she failed to win the title from Rousey. We then saw Jax losing a #1 contender's match on RAW this past week against Sasha Banks.
So, the only thing that the FaceBreaker can do at the Royal Rumble PPV is be a part of the 30 women Royal Rumble match and try to earn another shot at the Women's Championship.
#4 Tamina Snuka
Tamina Snuka is another female superstar who has no storyline or feud heading into the Royal Rumble PPV and so I expect her to be a part of the women's Royal Rumble match on the show.
The chances of Nia Jax or Tamina Snuka winning the Royal Rumble match are very low as the WWE Creative may want this tag team to be in the Women's tag team championship picture.