The credits of King of the Monsters have revealed that at some point after the fight ended, Rodan found a new volcano to take roost in. Rodan survived the events of King of the Monsters and is now a minion of Godzilla. Chen could be present when Mothra is reborn. Kong, this could be expanded on in the movie. King of the Monsters never had much of a chance to explore this connection on a deeper level, but with Zhang Ziyi reprising at least one of her roles in Godzilla vs. Through Zhang Ziyi's characters, the MonsterVerse has their own version of them, and Mothra was expecting to see when she first emerged. In Toho's Godzilla and Mothra movies, the Twin Fairies communicate directly with Mothra and share a strong bond with the character. As it turns out, the two represent the Twin Fairies from the classic Toho movies. Chen and her sister are the latest generation in a long line of twin sisters who have worked for Monarch. Chen in King of the Monsters, and for a brief scene, her twin sister, Ling.
It could be that there are plans for Mothra to made an immediate return, based on the casting of Zhang Ziyi, who played Dr. She could possibly return in Godzilla vs.