There's no word yet on if the returns are planned for Sunday's match, but PWInsider reports that they are both scheduled to be in Houston, Texas for the Rumble pay-per-view at Minute Maid Park.
Riott was at the WWE Performance Center earlier this month to train, as previously noted. It was noted that Riott is not expected to return to action until later this year, and was likely at the Performance Center to have her progress monitored towards getting medically cleared to return. Riott has been out of action since undergoing double shoulder surgery in 2019 - one operation on her right shoulder in May, the same operation on her left shoulder in August. She hasn't wrestled since the May 17, 2019 WWE live event from Cardiff, Wales, where she, Tamina Snuka, and Lacey Evans lost a Fatal 4 Way to RAW Women's Champion Becky Lynch. She hasn't wrestled a TV match since losing to Dana Brooke at the April 22, 2019 WWE Main Event tapings.
It was reported earlier this month that Jax could be returning to the ring soon, possibly in time for the Rumble. Jax underwent double knee surgery back on April 25 of last year and was said to be doing great, ahead of schedule with her recovery during the summer. It was reported in June that Jax should be back in time for the 2020 Rumble pay-per-view, but there haven't been many updates on her status since.
As noted earlier this week, Naomi is scheduled to be in Houston this weekend and there is talk of her returning in the Rumble Match on Sunday as well. She is currently scheduled to be sent to the SmackDown brand, as The Usos were when they returned.
WWE currently has just 5 spots announced for the 30-Woman Rumble Match - Charlotte Flair, Natalya, Nikki Cross, Alexa Bliss, and Sarah Logan.
Stay tuned for updates on Sunday's big event.