This gets into a deeper philosophical conversation of what is _legal_. Legality is a social construct. After the America civil war, the the succession of the South was declared illegal.
http://khanism.org/security/legality/
It was also once legal to own slaves and legal for merchants to deny sales and service to blacks. Homosexuality was once illegal. If there is enough moral outrage and enough of the population backing a movement, the legality can change since it is a pure social construct based the belief of the people.
For example, people in Texas who want a succession movement. It will never happen because although there are some very loud people for it, less than 2% of the entire population actually supports such an idea. If it one day changes to 60% ~ 70% .. or even up to 80%, what's legal at the Federal level simply won't matter. At that point we'll see the David Graeber argument play out; namely that States work because of their monopoly on violence.
We see this today when it comes to American states with recreational cannibals, illegal at the Federal level, yet socially and morally accepted within the states that have legalized it (Washington, Oregon, California, Nevada, Colorado, etc.)
Personally, I hope I see Cascadia succeeded in my lifetime. I think that would be awesome.