It is likely to be a tight race, but as long as Hillary Clinton's supporters come out to vote for her, she will win. While Trump has been gaining some momentum and supporters in the last few weeks, this does not mean that she will lose the race, as long as she continues to campaign.
Yes, Clinton will win Florida handily. The polls already show Clinton leading Trump by at least seven points. Since she has officially won the nomination of the democratic party, she is garnering more and more support from those who previously supported Sanders. As that support grows, she will be able to best Trump by even more points.
I do expect Clinton to win Florida, but I'd be shocked if anybody wins the state by 7 points. Florida is a historic battleground state that Obama won in 2012 by a 50-49 margin. In 2008 Obama won Florida, 51-48. The state will most likely be close again as it always is.
I don't believe that Clinton will handily win Florida. Although the NBC News poll shows a strong lead, I've seen other recent polls here in Florida that reflect the opposite. At this point, I think that either one of them still has a chance. It is very obvious that Clinton is really trying to win Florida, though, since it seems like every other commercial is an ad for her campaign.