IL should be a fairly boring state really. It is losing population and will be losing electoral votes next time too. Biden will see modest improvements in the chicagoland suburbs, and also in places like McLean county, where he is a good fit for and Trump is meh. Trump should improve in most of the rest of the state though that is not blue leaning already. The topline should be really stagnant, as it barely budged from 2012 to 2016, though as talked about already, there will be further polarization.
+17.07 Clinton to +17.31 Biden (0.24 margin swing dem)
I am surprised that a mega city like Chicago is losing people. It should be a Midwestern hub drawing in young people from rural areas in the Midwest and downstate IL.