This whole political race is like choosing if you want something bad or really bad. Do you want a liar or a jerk. It's a completely ridiculous choice to have to make but it must be made. Because of the nature of this specific race it will definitely come down to what a specific person will be more tolerant of. Since opinions are so varied that is going to make the race neck-to-neck until the very end.
The race has definitely been tightening, but CNN has been the only poll to show Trump clear the low 40's (he was at 48% in their inter-convention poll).
I am skeptical unless and until other live caller polls replicate these results. I note that they have Trump winning the white vote by about the same margin as Romney won over Obama (21 points). They also have Hillary winning the white college educated vote by 13 -- but still down by 2 overall? Basically, CNN is predicting an historically high uneducated white vote.
This election will not come down to the wire. Donald Trump is losing supporters left and right. Women do not support Donald Trump because of the many sexist things he has said. Donald Trump doesn't even have the full support of the GOP. Hillary Clinton is not that far to the left, so she will be able to pick up the supporters that Donald Trump loses. It will not be a close election.
These debates are predicted to be the most highly viewed presidential debates ever, greater than the 70 million people that watched Jimmy Carter against Ronald Reagan. This will mean that any positive result for either candidate will be amplified such that it will be hard for the other to recover the lost ground. This is typical of this polarising election, where views on both sides have been pushed to the ends of the spectrum, which results in reasonable and moderate views hard to find. Donald Trump has so far ridden a wave of anti-establishment prejudice, often at the expense of facts. If he can continue this and use his loud and emotive personality to dominate the debates, then he will win. However, the debates could brutally expose his lack of political experience and knowledge, which would push voters to Hillary Clinton, allowing her to win.