Tying it closer to I Have No Mouth would've been better, escape is impossible, Caine is an irredeemable menace, abstraction is proven to be a blissful-like state like the Jax dream.
Some plot device found by Caine permanently forces everyone to be unable to abstract anymore.
The gang finds another device that forces everyone to abstract but the operator is unable to and its one time use, they choose collective suicide but Pomni is the operator.
She becomes Caine's only remaining plaything. Cue formless great jelly thing many years later.