#3 Returns from injuries
In addition to returns and debuts, there are also some stars out with injury who make an impact by reappearing. The first name that comes to my mind is Nia Jax. She's been out for almost a year due to knee surgeries but was seen at the WWE PC prior to the Royal Rumble. She could be ready for a post-Mania return if cleared for action. Jax has also been posting photos of her training sessions on Twitter.
Jinder Mahal and Ember Moon are also out nursing injuries but Mahal is probably closer to a return than Moon. The Shenom revealed on Booker T's podcast that she tore her Achilles in September of 2019 during a 24/7 title segment. Those types of injuries can often take a year to heal but she could feasibly return beforehand depending on her healing ability.
While she's a member of NXT, Io Shirai is also out dealing with an injury. She was taken out of action in January of this year and was said to be out for two months. That would put her on track to either go back to NXT or debut on a main-roster brand following the Show of Shows. I personally think she should join RAW or SmackDown because both shows need a rejuvenation of talent.
I'm not sure if Shirai is going to slate back into the NXT Women's title picture because she, like Bianca Belair, has had a few unsuccessful attempts at capturing the title. The simple point is that reinforcements are on the way for the roster and some will show up once business is done in Tampa.