If Obama is re-elected there will likely be a surge in anything that looks like an assault rifle or has high capacity mags. I don't know that the surge would be justified or not but it would likely happen. Or perhaps that would just be a continuation of the current surge for anything that looks like an assault rifle?
From a collectors standpoint (at least financially speaking) the trick is to figure out what isn't selling but will.
As for what is currently selling (besides AR's, AK'S, and 1911's), I've really been surprised by the sells of Mosin Nagants. I'm not a fan of them. They're literally a step backwards in the evolution of firearms. Ironically though those guns weren't exactly state of the art when they were new. What led to their creation was the same things that are making them so popular now. Their price is cheap and they're extremely rugged. That's a powerful combination during war in a poor country, and during a prolonged economic recession.
Maybe I was wrong about Nagants being a step backwards in the evolution of firearms? It could be that their popularity represents a step backwards in economic and social progress? It's probably not a good sign when guns designed to cheaply arm peasants for war are all of a sudden extremely popular. Now that I think about it those guns were extremely well designed for their intended purpose. It isn't the gun I don't care for but the conditions that led to their design to begin with, and their resurgent in popularity. I guess history does repeat itself?
With all that being said, if things keep going like they are I could see flintlock muskets becoming a really hot item in a few years.