...it seems America is heading slowly in the right direction.
Wait, what? When did the world agree on the idea that "yeah, it would be better if all the minorities were represented in government and took office"? Also, do any of the above listed traits really MATTER in political decision making? Shouldn't experience, education, analytical capabilities, charisma and sensibility be more important than sexual preference or skin colour?
Well, that's exactly the point. Many of the groups of people listed above are de facto
excluded from high political office because of prejudice, irrespective of their actual qualifications.
To have a go at answering my own question, I think the US is basically ready for a female president (and Hilary would have been elected had she won the nomination back in '08), and possibly a Jewish one (remember Lieberman was a VP candidate in 2000), though a Jewish candidate would probably face heightened scrutiny. A Latino president is plausible, if not straight away, then maybe ten-fifteen years in the future.
We're still quite far away from the US being ready for a gay president, I think, but the trend is pretty clear. Maybe in thirty years?
Muslims, scientologists, Hindus or atheists don't stand a chance for the foreseeable future, and while that might change for some of the religions, the country would have to change fundamentally before it was open to an atheist president. (And Ali may be right that some of the Founding Fathers were privately atheist, and both Washington and Jefferson were certainly equivocal about many aspects of Christianity, but even back then it was politically necessary to be publicly religious.)
The US has had fat presidents in the past, of course, but I think it would be a very hard sell in modern American politics, somewhat ironically given the increase in obesity. It was often cited against Governor Christie's possible run. (Similarly, there have been bachelor presidents, but today I don't think an unmarried candidate could reach the office.)