It was utter nonsense, whipped up by the presence of X-Men TV series and some interestingly written press releases.
You can see by from them that while Fox makes a nod towards co-operation with Marvel, and lists a number of Marvel producers on the shows, it is notable that there is no quote from a Marvel rep, just Fox people. It is co-operation in name only, the producers mentioned are part of a legal agreement, they won't actually have anything to do with the shows. Fox have the full rights to make any live action TV shows based on the X-Men and Fantastic Four properties without interference.
Fox have no intention of letting the Fantastic Four rights slip, even after the performance of their third film. To maintain it, they have to do something but it doesn't need a feature film to maintain it. Hell, an appearance on Hellfire or Legion might do it. And it is an asset that it would seem foolish to let slip. The last time they did, they lost Daredevil. They're not letting that happen again.
While there are big problems between the Marvel Films side and the TV/games/comics side, and there have been suggestions that Marvel CEO Isaac Perlmutter may consider the enemy of his enemy is is friend and try to rectify things with Fox, at least as far the TV/games/comics are concerned. However, I'm told by reliable sources that this is not the case. Don't expect a Fantastic Four comic, or a line of X-Men games and toys any time soon, and expect Marvel Comics to continue to support Avengers, Guardians and Spider-Man for preference.
I understand that Perlmutter is playing the long game, believing that Marvel movie boss Kevin Feige will overspend and underperform on the Avengers movies and that will be his undoing.
The proof of the pudding will be in its box office performance…