Doctor Doom: the new origin story

Here's how I think they'll do it, given that the Russo brothers are back in charge and they're smart and so they know that casting Robert Downey Jr as an entirely different guy in the MCU would be pointless. Also they know that a villain called "Victor Von Doom" who wears medieval armour under a green cloak is pretty dumb. So it's obvious: Downey will be playing Tony Stark in the Fantastic Four's timeline. 

As in the regular timeline, Tony is injured by one of his own weapons -- and maybe also disfigured, though I suspect they'll drop that aspect of Dr Doom's origin as audiences will want to see him with the mask off. But things are different in this timeline. Maybe Pepper is with him in Afghanistan and gets killed. Maybe there's no Yinsen to point him on a better path. Maybe (oh, please) Raza is on course to becoming the real Mandarin and having him as a shadow-self only makes Tony more bitter and self-righteous.

Of course, in this timeline Tony has to be an old college buddy of Reed Richards at MIT, but after the death of his parents Tony went off to be a rapacious capitalist weapons dealer while Reed stuck with their youthful utopian ideals. As a brilliant but ruthless arms manufacturer Tony has dozens of nicknames on social media, one of which might well be "Doctor Doom". After he builds the suit (and note that the original suit design isn't far off the Kirby Doom's armour) he leans right into that soubriquet. Even so, through most of the movie I'll bet they'll be just "Tony" and "Reed" -- after all, there's not much that can be done with the name "Mister Fantastic" either except through the lens of irony.

And this will make for a much better character basis to the conflict. An old friendship gone sour, an antagonist who believes he's doing the right thing, regret at the path not taken, the faint possibility of redemption -- that will give a real spark to their dialogue together, and give us a chance to see Reed's fundamental decency contrasted with an arrogance we always half-knew only needed a nudge to go bad.

Or maybe I'm wrong and Anthony & Joseph Russo will come up with an even better way to work Robert Downey Jr logically into the Phase VI storyline. They've done some top-class work in the past, so I'm betting whatever they come up with will be worth the wait.