Well, every state has these kinds of people. I mean, so did California after all, and they did do a lot of protests -- it's not good to base the whole state on these kinds of people. There will be no amendment. I can promise that.
So, at minimum, five years of gay marriage in Iowa is now in the offing. And any such ban wouldn't take effect until November of 2014 at the earliest. Closer to six years than five, actually. That may actually be enough time for opinions in Iowa to change to the point where the Christers can't muster 50% + 1 at the ballot. Maybe.
In a year or two, it won't be an issue anymore except for the sort of people in your first post(but it might still seem like one because they're just loud). By 2014, a ban would lose.
They
could have little victories though - like passing a law that requires a couple to be Iowa citizens to get married there. Little things like that that aren't too big of a deal but still suck if you're an out-of-stater.