Illinois and Maine I think are too Democratic as states to go Republican.
Governorships are not as partisan as Senate seats or presidential elections. The deepest red state (like Wyoming) can elect a Democratic governor while a deep blue state (like Vermont or RI) can elect a Republican governor.
That is true, but it still matters. a), If the state party is in really bad shape, like the GOP in Illinois is. Secondly, most of the time a state aligned towards one party will vote for it unless they have a good reason not to. I'm not seeing that reason in Maine. Thirdly, I suspect that ticket-splitting will continue its decline in the last years. The country is increasingly polarized and as a lot of Democrats and Republicans have discovered in the last years it's getting increasingly difficult to win at all levels in hostile states. Look at how the Democrats in the last years have lost positions in the South, for instance. Most places that have shown remarkable differences between presidential voting and state-wide voting are becoming more monlithic (MA, NY in this cycle, many Southern states previously).
Obviously, people will still get elected from states strongly for the other party, but not if they don't give the voters a good reason.
