Yeah, Multiversity stuff is coming, but in the form of OGNs, and the MULTIVERSITY title is really just a marketing gimmick to tell whatever weird, wonderful stories Morrison has in mind for superheroes.
The first one is going to be his FLASH story, which had nothing to do with Multiversity per se; it was just a grounded take on the Flash. I believe it was originally developed as a Screenplay for a Live Action film (Morrison was a consultant on DC films a while ago), and then he talked about re-purposing it for a Flash: Earth One story. Instead they just decided to give Morrison free reign to do whatever he wants with his unused superhero ideas in MULTIVERSITY TOO and BATMAN BLACK & WHITE, which I am 100% a-okay with.
They talked about other, Morrison-picked creators being a part of that line, and I know he's pretty friendly with John Hickman (John was a guest at MorrisonCon), so that's sort of where I expect to see him, if anywhere at DC.