When Superman began to outlive his friends and loved one he left Earth to explore the depths of space. However he did not leave his adopted planet unprotected, as he left the hero Secundus to be the new Superman and carry on his legacy. Secundus fought the living computer Solaris and other villians, and began the Superman Dynasty.
Later Secundus was seen wearing a new uniform, fighting Epoch alongside Damian Wayne as the new Batman.
It was revealed by All Star creator, Grant Morrison than Superman Secundus (Superman 2) made an appearance in All Star Superman 6, as the son hinted in the end of the series. In the All Star continuity, Superman Secundus was conceived from the mix of Superman DNA and superwered Lois Lane DNA, following Superman instructions. The child was devlopted by Leo Quintum after Superman apparent passing and he would grow to join the Superman Squad and the Supermen of the Multiverse and share adventures with his time traveling father and with his own descendants.
Visually, in the All Star continuity, his look is based in other "sons of Superman": Captain Marvel and Marvelman. So he uses the yellow cummerbund around his waist from Captain Marvel, while his gloves, boots and the lack of a cape recall Marvelman.