I just wrote that in the Avengers thread a few minutes ago...
"That would make Iron Man the first superhero in the world to have his own film trilogy and not fight his archfoe from the comics in it!
And, responding to someone pointing out that "racist caricature" thing:
"In their early years, Wasp and Invisible Girl were sexist caricatures. Helpless females who always need powerful men to rescue them.
And what are they today? It's not that difficult to 'upgrade' a character a little bit by creating a new interpretation of him...
The Mandarin was good enough for the 2007 animated movie 'The Invincible Iron Man' (Lionsgate). So I don't see any reason why he shouldn't work for IM3. "
Honestly, an Iron Man trilogy without the Mandarin doesn't make much sense to me.