Here's a Democratic landslide based on a caricature of present trends:
Unless something in our economy happens to disrupt the disconnect between large/connected metros and the rest of the country, especially the small towns and cities of the Midwest, I doubt that we'll see Republicans improving in the former or Democrats improving in the latter.
Playing Devil's advocate, Trump won Wyoming by 118,000 votes. Weld County, CO has added 133,000 residents over the past 18 years. If the I-25 sprawl swallows up Cheyenne, it wouldn't take very long to make the state competitive.
Weld County voted Trump by over 20 points and trended R in 2016. Even when assuming these areas are going to keep growing indefinitely, the amount of time it would take for Laramie county to become large and profoundly blue enough to flip Wyoming in this paradigm would be so long that by the time it happens the GOP already would have already adapted to the significantly more urban environment in order to remain electable thus making this extrapolation useless.
