<p>It seems to me there are two questions here: first, if you take a gap year, and retake the SAT with much higher scores, will you have a chance of admission to the schools that rejected you, or similar ones? The answer to this is: maybe. It is up to you to decide if your interest in those schools is strong enough to take that risk. For some people, it is.
The other question, if I understand it, is whether if you enroll at a university in your home country, you can still apply to US universities as a freshman after a year. I have always understood that you generally could NOT do this. You have to research this carefully, and ask the schools you are interested in what their policy is. As others have noted, it can be very difficult to transfer.</p>