Bleeding Cool just published a piece about how a new Swamp Thing series may have been binned at Vertigo. But why?
Well, a few issues into production on the new book, I'm told that the work came down from on High. Co-publisher Dan DiDio decreed that Swamp Thing was to return back to the purvue of the DC Universe, the superhero line. There will be a new Swamp Thing series, creative team as yet unconfirmed, interacting with the Justice League and the like, something generally frowned upon at Vertigo these days.
When proto-Vertigo titles began, they commonly interacted with the rest of DC Comics. Swamp Thing guest starred Batman and Superman, the Justice League appeared in Sandman and Books Of Magic saw Tim Hunter on a tour of the whole DC magical universe. But the Vertigo line mostly put a stop to that sort of thing, a separation between suitable-for-younger-readers and mature readers was deemed necessary, especially by Paul Levitz.
Although with recent DCU storylines, that difference is pretty moot right now, aside from occasional flashes of nudity and the odd "fuck" or two.
I understand from speaking to a number of people that the new policy is that any character that came from the DC Universe can and will be used by the DC Universe. Prez, Black Orchid, Shade, they're all back up for grabs.
Not exactly sure how that will affect John Constantine though… though I'd probably buy a Constantine/Batman book if they ever came up with one.