Polarization is high, but Montana isn't quite comparable to North Dakota or Tennessee, since it's much less red, and is even more competitive at the statewide level. Assuming Bullock is in, this is definitely a race to watch and certainly has potential to flip, but I think calling it more likely to flip than AZ/NC might be jumping the gun a bit, since Trump could lose both of those states (or even conceivably GA or *IOWA*, yes, I went there
) if he's having a bad night, but there's no way he's going to come close to losing Montana even in a Democratic wave. So Bullock still has to win over a significant number of Trump voters, which is increasingly hard to do.