It should be noted that Hypertime was reconned long ago.
So Hypertime doesn't exist in the DC Universe anymore.
I sincerely hope this isn't true; having Kathy Kane show up in a Bat-book made my day. Unlike other historical plot elements, she barely shows up in ELSEWORLDS.
Alan Moore is a really big fan of Kathy Kane; for instance, he mentioned Batman was married to her in the fantasy created by Mongul's Black Orchid (though really, IMHO, I think it ought to have been Silver St. Cloud, but that's no reflection on the neatness of this character). Also, in his TRIAL OF YOUNGBLOOD, he created a Kathy Kane pastiche character, "Lady Day."
It irks me that THE KINGDOM and its concepts are demonized by fans. KINGDOM COME suffered from all the plot holes, implausibility, and characterization lapses that its sequel had, except there was no Alex Ross art to make us forget. And at least THE KINGDOM gave us the gift of Hypertime. Want the Atomic Knights to appear in your story, but don't want to say they're the "real" future? Hypertime solved a great many problems and made a great many stories possible that its exclusion is tragic.
As for Byrne being a racist - well, maybe "racial chauvanist" is a better term. His lack of sympathy for the New Orleans victims shows his problem is more about CLASS than RACE.
And the fact that they're acknowledging a multiverse of some kind again is just a different flavour of the same deal. If the multiverse is being acknowledged again, then the Atomic Knights, etc. still exist in their own DC realities.
Hopefully!