Superman: He'd be a modern version of his Golden Age self. In other words, Superman from Grant Morrison's New 52 run.
Batman: Still the same, except there'd be more examination of him being a rich white guy. Either Gordon or Robin becomes a POC.
Wonder Woman: Basically agree with what others have said. Still the same, except it'd be very clear that she's LGBT+.
Aquaman: Definitely Polynesian like the DCEU version.
The Flash: Pretty much modern Barry, except Asian.
Green Lantern: John is the main GL, but is given Hal's rogues gallery and relationship with Sinestro.