According to Den of Geek, the rights to The Fantastic Four may have been returned to Marvel.
"Fox were given the TV rights for X-Men in exchange for Fantastic Four," they write. "The deal's been in the works for some time, we're told, and further, the timing of Marvel's recent announcement of its movie slate leading up to the year 2020 and the X-Men TV series is no coincidence." They cite an unnamed source and warn they could not find another to back up the claim.
It has the ring of wishful thinking, but it makes a certain amount of sense after yesterday's announcement of two television series based on X-Men in the works; Legion and Hellfire. At the same time, that amount of sense makes it pretty easy to jump to the conclusion that Marvel made some sort of deal to reacquire The Fantastic Four by giving up more X-Men ground. Provided, of course, Marvel even has X-Men TV rights to barter with.
Considering the effort Fox put into insuring a Fantastic Four film would be in production before their option expired, it would be surprising to see them return it at this point. To do so would suggest they now see the property as completely spoiled goods.
UPDATE: According to Entertainment Weekly's Anthony Breznican, the rumor is not true.
Spoke with Fox and Marvel and both sides confirm: Fantastic Four is still with Fox. No change of hands.
— Anthony Breznican (@Breznican) October 15, 2015