Remember that although Trump was consistently favored to win Iowa during the last 2-3 months or so of the 2016 election campaign, most polls suggested that he would only win by about 2-4% instead of 8-10%. Thus, I wouldn't say that IA is a "lost cause" for Democrats - I believe they can easily reclaim it if they run a candidate who actively connects with working class voters there (like Obama did back in 2008 & 2012).
I actually remember thinking that Clinton would win Iowa even after polls showed Trump ahead, as I thought the signs pointed to a general national Clinton beats her poll numbers election.