Trank has been on film since 2012.It has been In works for 2 years.Many films take awhile to get off the ground.
Longer than that. They announced the reboot the day after Disney bought Marvel out (...ahem..). That's nearing
5 years
now.
The timeline is roughly as follows:
Aug 2009....and so it begins...Fox announces a Fantastic Four reboot. Akiva Goldsman was hired as a producer and Michael Green as the screenwriter. I think it was initially 'pencilled' in for a 2011 release but that was never realistic.
Then nothing but casting rumours until early 2012 when Trank's name was first being touted as Director. He denied he had the gig then, but was confirmed by July 2012, nearly 3 years after the reboot was first announced (perhaps when Fox realised no big cheque was looming from the Mouse...) and Jeremy Slater was now announced as the screenwriter.
Feb 13 Mathew Vaughan is now attached as a producer and Seth Graham Smith now brought in to 'polish' the script. Throughout 2013 there were casting calls for location shooting dates that never materialised. MBJ was rumoured as a lock for the role of Johnny as early as May 2013 with
none of the rest of the cast even tested until early this year.
In October 13 Simon Kinberg was brought in as a producer and co/re-writes the script, and appears to have replaced Mark Millar as an official mouthpiece for this film.
December 2013 Fox announce a March 6th 2015 release date, changed not long after to June 19th.
More location shoots early this year deferred until finally in early May (and possibly not very far from the expiry deadline) the camera's finally started rolling.
There's more to all this, but these are the main things I can remember and could easily find for confirmation on dates.
Compare the production of DOFP to this...DOFP was pitched in
2011, Kinberg began on that script in November 2011, and it was all done & dusted by this year. About 2.5 years years there, while this film will have been nearly
6 years in the making by the time it hits the theatres.