This sort of sounds like bad news and good news on the Fantastic Four reboot. According to The Hollywood Reporter, Simon Kinberg is being brought in to work on the script for the Fantastic Four reboot. Their sources indicate that he may be "overhauling the script substantially."
Of course, it's usually considered bad news whenever a studio brings in a new writer to do a substantial overhaul, because it usually indicates that the studio isn't satisfied with the script that they have. However, it's also good news because Kinberg is known in the industry for successfully reworking scripts.
Also, Kinberg was a scriptwriter on X-Men: Days Of Future Past, which must mean the studio is really happy with the way that script turned out if they are bringing him in for Fantastic Four.
Kinberg will also reportedly be serving as a producer on the Fantastic Four reboot along with Matthew Vaughn. With Josh Trank directing and both Kinberg and Vaughn producing, FOX is definitely throwing a lot of talent at Fantastic Four, which could turn out to be a very good thing.