If someone is telling you that the US 'may soon legalize online gambling' then you are not listening to someone who understands US policy making. I expect that the US will legalize marijuana before they legalize gambling, and making pot legal is at least a decade away, maybe two.

The reasoning is two fold, first gambling is considered a 'sin' by many religions (which is why Las Vegas was sometimes called 'sin city') as was same sex marriage. There is a chance we will finally clear the way for same sex marriage after a decade of staunch resistance by religious interests, and if they 'lose' that fight they will certainly try to draw a line in the sand with gambling. These same interests have been trying over turn the right to privacy ruling which made abortion legal.

EDIT: add reasoning.