I believe this last fall and winter surprised with some higher crowd levels, and it seems that crowds have been shifting from summer to other months. 
But, could we see a dip this fall and winter because folks are holding-out for Star Wars? If so, will it still feel crowded because WDW will reduce ride capacity? Please speculate mildly or wildly…
Based on past years and hearing some of the difficulties people have had with scheduling ADRs, my guess is fall will be crowded. Star Wars GE won’t be open until late fall 2019, so I don’t see that affecting the end of 2018 very much.