I predict Montana loses this round.
It might be a Pyrrhic victory for the feds. They get the ruling they want, but it just pisses off freedom lovers and state legislatures even more.
Besides, there’s the never-addressed conflict of interest issue. How many states are going to view as illegitimate the ruling of a branch of the federal government, in favor of the federal government? Perhaps state vs. fed issues should be decided by a panel of jurists from other states.
More like the feds will proclaim that Montana loses. Whether or not they actually do depends on the people and State officials of Montana. If the State of Montana is willing to actually defend the rights of the people they will tell the feds "NO, WE REALLY MEAN IT" and any agents sent to enforce their federal proclamation will be jailed.
Tenth Amendment and all that… We will see if Montana is serious about this.
Although if this many states are introducing measures, you’d think they could go for a Constitutional Amendment. In which case the feds might lose. (But, not with the current Congress.)