Kevin Feige on plans for the X-Men and the Fantastic Four. Basically, there aren't any. Stating that the deal wasn't even official yet and that whatever talks were happening were well above his pay grade, he is focusing on what has already been announced and is in development, which would take us to 2020 at minimum. If and when he actually and officially gets his hands on the characters, then he will start developing ideas.
http://www.vulture.com/2018/01/kevin-feige-on-the-disney-fox-merger-his-future-at-marvel.html
http://www.vulture.com/2018/01/kevin-feige-on-the-disney-fox-merger-his-future-at-marvel.html