The only way Hillary Clinton will defeat Trump in a landslide is if she gets Sanders or her husband former president Bill Clinton to be her running mate. She more than likely will NOT do that so it will be a very close race because nobody really likes either one of the candidates but they hate her less than they do Trump.
I feel the majority of the country is still hoping for some last minute miracle of someone with sense running for President. Hillary holding strong in swing states does not indicate a landslide in the least. Candidates will be pushing to the very end on the amount of strength needed to take over office and be a strong President. Polls don't always reflect the outcome.
I think that Clinton will win the election, but probably not in a landslide. There are enough people who dislike or even hate her, for various reasons, that she will have a difficult time winning. However, in the end, more people dislike Trump, so Clinton will win a close race, as the lesser of two evils.
I don't think that Clinton will win in a landslide in November. I think both candidates still have a shot, and the polls will rise and fall over the next few months. In addition, the polls are very confusing. I just read a poll this morning that projected Trump would have a huge lead in Florida, an important swing state.