I think it will be really interesting to see what happens in election forecasting if Trump wins this election -- doubly so if there's no major scandal for Clinton between now and election day.
If the polls stay as they are and the election goes the other way, it means that polling as practiced is somehow fundamentally broken, which would be very surprising.
If there's a gradual shift in the polls, I'm not sure what that would mean. Which scenario did you have in mind?
Nate Silver arguably lost a good deal of "prediction calibration points" by placing a very low chance on Trump getting the nomination in the first place.
And wouldn't the same be true if Trump wins the election? After all, Nate Silver isn't predicting a 0% chance for Trump to win, I think last time I checked it was 10-15%.