A low population state is always easier to flip if you create the circumstances needed for sudden inmigration of people from other parts of America who have different outlooks (e.g. urban vs.rural). If, somehow, a major employer (like a tech company) moved there from California, it would have an effect. The problem, of course, is the severity of Wyoming's climate. Low population states are that way for reasons that are often obvious.
A harsh climate by itself doesn't necessarily stop a place from attracting a lot of transplants. Look at Madison, Grand Rapids or the Twin Cities.
Anyway, Trump won Wyoming by about 120K votes. The way to flip it would be to somehow turn Cheyenne or Casper into a boomtown that attracts a lot of young liberals. Preferably from California, where Democrats have
tons of votes to spare.