My guess is this is for all the people who want "their" DCU back. If it's an infinite multiverse than any combination of universes could be out there. Pick your favorite era and it probably has it's own universe now. Not that they'll be getting their own series anytime soon but if you liked Mullet Superman or Atlantean Power Girl or Hawkworld Hawkman, they probably exist somewhere out there in the multiverse. Apparently this "new" multiverse is also including things like movies and TV shows too. So Teen Titans Go! can team up with Zack Snyder's Justice League if you wanted.