Personally I think it will be a deep republican state that is very elastic. So probably a state like North Dakota.
I agree with this. In 2008, Obama won 44 and 47.5% of the vote in each of MT, SD, and ND; Clinton won 27% in ND, 32% in SD, and 36% in MT. I could see these states swinging strongly towards Democrats but still not being competitive.
Among swing(ish) states, I could see OH and IA being much more competitive than in 2016. Democrats could get an extra 5 percent in either state and still come up short.