There will never be a decent Fantastic Four movie. Forget about whether there can be a great one, think "decent", the kind where after you've seen it you would not think it punishment it see it again.
Oh, well, if we count Brad Bird's The Incredibles we have what could have been a Fantastic Four movie ... .
No story that tries to shoe-horn Doctor Doom into the origin story is going to work. We've had more than a decade to consider superhero films as a genre and a Fantastic Four movie that insists on a single originating process for both the heroes and their archnemesis is doomed to failure.
Let's go back to the heady days of the genre. Sam Raimi's first Spider-man film gave us a hero and a villain with PARALLEL origin stories but the stories reflected their different views about access to and use of power. It was okay for the hero and his or her nemesis to have parallel paths that culminated in a confrontation. What has come up in reviews of the clunky Fantastic Four films is we're told that the heroes have to stop the threat of a menace they have explicitly created or that is pretty much their fault. This could get me on a long tangent about why Legend of Korra is a trainwreck but we'll save that for later.
Skipping past Spider-man let's get to Batman Begins. Bruce Wayne is mentored by Ducard who turns out to be Ra's al Ghul. In this case the surrogate father turns out to be evil but since Thomas Wayne is presented as heroic, as someone from old money who believes money and power should be used to serve the community you live with, not to bend and break it into subservience to your individual vision and will, that makes sense. It doesn't breach our popular sensibility that the hero and the villain have different moral paradigms and it doesn't breach the popular genre sensibility that the hero and the villain have a conflict based on an irreconcilable difference about the use and access to power.
Now in having proposed that there's a problem with making the origin of the Fantastic Four and the origin of Doctor Doom the same inciting incident Wenatchee The Hatchet has not forgotten about Captain America. Yeah, Red Skull and Cap both take the super soldier serum. Dr. Erskine tells a story of how the Red Skull became the Red Skull and so attempting to give the serum to Steve Rogers becomes a path of atonement for Dr. Erskine. Erskine knows the serum was given to a morally unworthy test subject even if he was physically compatible with the project. Thus Erskine turns to Rogers as a new test subject as a kind of penance but also as a choice to give the power to someone who is not physically worthy of it and might potentially not survive the process but who Erskine considers morally able to handle the power if he should survive long enough to receive it. It all boils down to Steve answering Dr. Erskine's, "So, do you want to kill Nazis?" with "I don't WANT to kill anybody."
So while the serum is the same serum, the taxonomy of the hero and the villain having divergent origins is still preserved.
One of the mistakes in genre fiction, but particularly in the superhero genre in the last twenty years, is fixating on this idea that the origin story or backstory has talismanic power. Superman and Batman did not start with particularly grand origin stories. And in the case of villains there's little need for an origin story. The Dark Knight gave us a Joker who didn't even have a coherent origin story.
But Saint Augustine, way back in City of God, wrote that he could ultimately find neither a natural nor efficient cause for the origin of the evil will. It was mysterious where the origin of the evil will was on "natural" grounds because if God made all things good then where did that evil will come from? From nature? This did not seem possible. There was no "efficient" cause in the sense that while the Genesis 3 narrative could describe how the fruit was desirable as the serpent persuaded Eve there's no efficient explanation for a process as to how the evil will emerged, either. It kinda just shows up.
As an aside, one of the things that seems most pernicious about a Silence of Adam theology of gender is how sweeping it is in frontloading contemporary sexuality and gender anxiety issues on to a biblical text that seems blissfully unconcerned with giving us a Dostoevsky style portrait of the interior emotional, intellectual and spiritual life of Adam and Eve.
Now that Doctor Doom almost seems like a Gary Stue is something else for some other time. If there's going to be a decent Fantastic Four film don't cram Doom into the origin story. Why should Doom be sullied by having an origin story that is so contingent on the accidental empowerment of the clod Reed Richards? Let Doom have Doom's own origin story on Doom's terms alone. Or take a cue from Nolan, who didn't introduce the Joker until he'd gotten us to take an interest in Batman first.