Hit me. What's wrong with this movie? (Presuming it is based on the Ultimate Fantastic Four comics)
Let's see:
The film is a reboot of a terrible film duology that experienced a 12.5% drop off in box office from the first movie to the sequel. FOX announced the reboot shortly after the sale to Disney back in 2009, but held off on production for as long they possibly could in order to play "keep away" with the character rights.
ROTSS cost $130 million, and looked very cheaply made. The FF team members all require expensive CGI to portray convincingly onscreen (especially the Thing), so to match the spectacle that current comic book audience demands, the budget will have to be raised significantly or look terrible. But the box office potential for a March release of a poorly received recent reboot won't allow this.
With Disney/Marvel controlling the merchandise rights, FOX will lose a significant revenue steam they had with the Tim Story films. Additional budget cutting will be required.
The reboot will be harmed by not being a part of the MCU, both by not having the branding of the wildly successful film universe but also by not having access to key characters in the team's history - Namor, the Hulk, the Inhumans (especially Crystal and Medusa), and the Black Panther.
The "all 26 year olds" casting is just awful, regardless of the actors skill.
The idea to mix and match the FF with the X-Men is terrible, and my not be permissable under the terms of the existing contracts with Disney/Marvel.
Josh Trank is talented, but he has just one very low budget film under his belt.
This is 1994 all over again - a film studio is going to crap out a version of the FF, this time in order to extort some cash from the Mouse.