Everyone is saying (and I agree) how much they loved that Pepper didn't get with Tony at the end! ...so, what is the vast majority of fanfic going to be? PEPPER GETTING WITH TONY AT THE END. Oh, fandom.
In all seriousness, I predict that IRON MAN movieverse fic will at some point lead to a massive ideological flame war, because -- let's be blunt -- with movieverse Tony being movieverse Tony, and Pepper being the one who clearly understands why the two of them getting together would be a Bad Idea, the fan-writer dealing with Tony overcoming Pepper's reluctance is going to have to be really damn careful to not write "sexual harassment, yay!" And I hate to say this, but fandom is NOT THAT CAREFUL IN ITS PURSUIT OF THE HOT. And it seems like nothing really pisses fandom off like conflicts between ideology and what people find hot.
You watch! It'll happen! Until then, maybe we'll get some terrific fic.