What would the DCU be like if Superman hadn't come back?

Possible scenerios...

Legion of Supermen continues.

Henshaw eventually takes over (no chance for Kon El to be the succesor)

JLA disband.

Coast City is never destroyed.

Hal remains GL (the question here is would he eventually become Parallax)

Finally...The Spectre uses Clark's body as a host.

Just remember - outside of the comics world, there's been a long-running court battle about ownership of Superman & related properties; the relatives & estates of Jerry Siegel & Joe Shuster vs. DC Comics. There's been a small chance of Supes leaving DC for years now, as a result. Imagine him moving to Marvel Comics. 😱 What kind of storyline could DC create to say goodbye to him?

Bruce and Diana would have sex.