Actually Dem turnout was down 20% and GOP turnout was up 60% this cycle and many polls haven't taken that into consideration.
Without the excitement generated by Sanders in the primary, Dem turnout in the general will be lower and if Trump steals the black vote lower still.
Well worth repeating. The GOP primary turnout was way up. While detractors note Trump got relatively small total percent in winning, he got the biggest popular vote ever, for primaries. And there were 17 candidates to begin, and several stayed in a long time.
For the dems, even with Sanders, they had dismal totals.
But the professional polling formulas apply the same GOP/dem/other weighting, as used in 2012. IOW they do NOT account for the additions for Trump.
And the democrat weighting does NOT account for the fact Sanders voters may not support her cankleness. Some progressives go to Jill Stein, some even to Gary Reefertarian Johnson.