Warning: Spoilers for The Flash season 8, episode 15, «Into the Still Force.»
The events of The Flash season 8, episode 15 presented a number of Easter eggs regarding the future of the Arrowverse and Barry Allen's friends and family. Most of these glimpses came through Barry's journey into the Still Force, which allows for instantaneous temporal travel between all points past, present, and future. However, some of these hints also came about through the ongoing subplots centering around the other members of Team Flash, such as Dr. Caitlin Snow teaming up with Chillblaine to resurrect the recently deceased Frost.
The main story of The Flash season 8, episode 15, «Into the Still Force,» centered around Barry Allen (Grant Gustin) as he searched for his missing wife, Iris (Candice Patton), who was suffering from a strange time sickness that caused her and objects and people around her to become randomly unstuck in both time and space. This illness was recently determined to have spread into the Still Force and to have infected its avatar, Deon Owens (Christian Magby), as he attempted to treat Iris. This led Deon to approach Barry for help in exploring the increasingly unstable Still Force dimension, claiming that his fellow cosmic Force hosts had vanished and that he feared the time virus had already destroyed them.
Related: The Flash Is Teasing A Major Team Change (It Needs To Happen)
The trip into the Still Force offered a number of glimpses into the future of the Arrowverse and several upcoming storylines and characters. Yet the events of the episode also helped to establish key facts regarding the future of Central City 2049 and the new version of XS created following the erasure of the original XS in The Flash season
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