In ACTION COMICS 287, Supergirl travels to the "21st century" to visit the Legion, where she encounters the Positive Man and the Negative Creature, then tangles with the Chameleon Men and is assisted by "Whizzy, descendant of famed Supercat Streaky."



Note: When the two Red-Caped Companions are consigned to the Phantom Zone by the Chameleon Cohorts, Supergirl observes that the Phantom Zone is empty--all the previous occupants having already won their freedom. But Mon-El should still be there--retroactively in continuity he must be. On the other hand, this story happened in the 21st century, so it might have been in an alternate timeline.

While Streaky is acknowledged as a famed Supercat in the future, once Linda's cat moves into the Danvers home and away from the X-Kryptonite at Midvale Orphange, he sees a lot less action in the Supergirl feature; nevertheless, as a member of the legendary Legion of Super-Pets, the Feisty Feline continues to appear in lots of other adventures. There must be some extra X-Kryptonite around for Streaky to power-up; I would guess Krypto and Comet know how to hook him up to get his fix of the junk. Metafeline genetics being what they are, Streaky must have passed on his powers to future litters.