The question, to my mind, isn't whether the federal courts will uphold Montana's statute (they won't, under over a century of an incredibly expansionist view of the interstate commerce clause), but what Montana will do when the dust has settled. There are many who believe that Montana's next shot will be to attempt secession. Should be interesting.
Yeah, I see that
A) Even assuming the "natives" would get behind it, increased migration into the state from places that aren't
crazy pretty much guarantees that secession would not have the level of support needed to go forward.
B) Secession ain't legal. Whether you think it should
be, and whether you're interested in arguing the validity of this legal fact, does not change the fact that the federal government isn't going to let Montana go.
C) Even assuming popular support could be gained, and even assuming you somehow managed to successfully secede (peacefully or through force), I'm pretty sure Montana would quickly descend to the level of third world craphole. Nothing against Montana, or the people here; I'd say the same about most
(and possibly all
) states, as well as most regions. Though I think this holds true for Montana more than some others. The United States is truly more than the sum of its parts.
EDIT: Basically talks of secession, particularly by individual states, always make me chuckle.