Several stories Post-Crisis hinted that Kara's ghost wandered over New Earth. What if she saw everything what happened between Linda and her younger self? Adding to that, what if she saw what happened to her best friend Barbara?
Infinite Crisis came out less than two years after the end of Many Happy Returns. The four survivors of The Multiverse saw this story's events playing out. Earth-Two Superman watched how his Earth-One cousin -to whom he owed his life- was ignored by Post-Crisis Superman and hurt and mistreated by other people -who were alive thanks to her-, whereas the human girl who took up the Supergirl's mantle got screwed up. Undoubtedly it cemented his belief that Earth could not be saved.
