When James Gunn presented the first wave of movies and shows that would kickstart the new DC Universe, he mentioned that Swamp Thing is one of them. And the project seems to be moving forward, and has landed James Mangold as director.
He is no stranger to superhero movies and has previously made both The Wolverine and Logan, although he is probably currently most known for the upcoming Indiana Jones film The Dial of Destiny. Speaking to Variety, Mangold explains how Swamp Thing will fit into the new DC Universe, and his response is at least somewhat surprising:
"While I'm sure DC views Swamp Thing as a franchise, I would be viewing it as a very simple, clean, Gothic horror movie about this man/monster... Just doing my own thing with this, just a standalone."
So while everything seems to happen in the same universe in the DC reboot, it doesn't necessarily mean that the superheroes will visit one another all the time. We assume James Gunn and Peter Safran want to establish the various characters first before starting mixing things up, which is probably a good idea.