When talking about his Larfleeze book to ComicBook.com, Keith Giffen answered the question
Since you're working with Marc [DeMatteis] again, how long until we get a guest issue from Kevin Maguire?
With this response;
Probably never since he's working on another book with me and Marc. I know that should be "Marc and me" but the thought of putting his name first… cue frisson.
A book with Giffen, DeMatteis and Maguire? The Justice League dream team?
It's happening folks. Well, I mean, something is.