Board Thread:Questions and Answers/@comment-26335203-20150801172956/@comment-6331988-20150801232414

Not that I know of, but it is strongly hinted at in All-Star Superman when Superman asks Superman Prime One Million which of his descendants he is, and Superman Prime One Million laughs. In DC One Million, Solaris is said to be Superman's greatest enemy, and he is shown to be responsible for Superman's "death" in All-Star Superman. This suggests that they are the same person, even if it isn't explicitly confirmed.