Mysterio is under contract with Lucha Underground through the end of season three, which will air in September. He'll be a free agent after that but has a 90-day non-compete agreement attached to his deal.
WWE is still searching for a big Latino star after failing to replace Mysterio in the first place. GFW had been pushing Alberto El Patron, who has had a lot of negative press from his tumultuous relationship with Paige. The current GFW World Heavyweight Champion is suspended indefinitely following a domestic dispute with Paige at the Orlando airport last week. Sports Illustrated noted that, "GFW/Impact is very motivated to move away from Alberto El Patron and generate some positive headlines by inking the legendary Mysterio."
Mysterio, 42, left WWE in February 2015 but has been open to the idea of returning for over a year. His son, Dominick, is looking to follow in his father's footsteps so Mysterio could opt to return to WWE in hopes that it helps his son's future.
Lucha Underground could look to retain Mysterio but will likely have a difficult time out-biding WWE should they decide they want to bring him back. They have also not announced plans for a fourth season.
Charles Maynard contributed to this article.