I made this suggestion months ago on Twitter when speaking with a mutual, and my theory took off, but I wanted to share it here to see what your thoughts are.

The way Marvel should reveal Doctor Doom's origins in Avengers: Doomsday is through Sentry, a member of the Thunderbolts, who is also the Void.

How I would have the scene play is that it starts with Doctor Doom annihilating The Thunderbolts. But the last ones standing are Bucky Barnes/Winter Soldier and Yelena Belova/Black Widow.

Doom will have a personal vendetta with Bucky (if Doctor Dooms end up being Tony Stark) and Yelena's final death is because Bob Reynolds is the closest to her.

Yelena's death sends Bob spiraling out of control and he becomes the Void and this puts Doom in a vulnerable state for the first time.

Then, we get flashbacks of Doctor Doom's origins. We learn about his friendship with Reed Richards, how he got scared, etc.
The Void is how Doctor Doom origins should be revealed