This has happened... See 'Infamous Iron Man'.
I read dr strange
It was actually an amazing series.
Doom became the infamous iron man after tony went into a coma after civil war II.
That was Alternate Version
No, that was main earth universe 616
Like mentionned above, Doom impersonating Iron Man (for a while, even) is totally canon for Earth616 (Infamous Iron Man series)...Like Doc Octopus being Spider Man in Superior Spider Man, in a less drastic way.
But... What If ... Iron Man becomes Doctor Doom? Tony Stark as the new regent of Latveria, a technological utopia managed by Ironbots and AIs...
The Doctor recommends Iron..
What do you think?