As Donald Trump continues to have problems with his campaign and people increasingly see him for what he really is, Hillary Clinton's poll numbers can only improve. Hillary continues to hone her message and manifest to the American people her competency, and the gulf between her and Donald Trump is widening.
Compared to the number of people in the United States, not that many people voted for Donald Trump in the primaries. It is very unlikely that someone other than a career politician or a military general would win the office of the Presidency. A lot of people think that because Clinton is experienced in politics, she is the better choice, regardless of whether that experience is positive.
No, Clinton's margin in the polls is not likely to increase in the coming months. Most voters are fairly set in their voting decisions. The only likely difference in numbers will come from swing, or undecided voters. These individuals will not likely make up their minds until November when they are forced to come to a decision.
I don't think that Clinton will end up winning the White House in November. The poll numbers change on a weekly basis, and they can be strongly skewed by the way that they are performed. Hillary just has too much scandal in her past and present for people to trust her as President.