Rising popularity has me worried we could easily see a ban if it really booms. I'd like to think all the research that's been done in the wake of the european ban (and german ban reversal) would be enough for the the u.s. government to leave it be. But they seem to love slapping bans on things without much consideration.
Buying a stash would be useless for me, I easily go through a pound every 1.5 - 2 weeks. Depending on strength. That adds up too quickly, to buy in one big haul. What I would most likely do, is see if my local polynesian community is still getting it in somehow. If, not, I'd probably move to Hawai'i. Although Hawai'i is the US and it hypothetically be banned there too, they wouldn't be able to regulate the fact that it grows there. It will always be in supply in Hawai'i and perhaps Hawai'i would be exempt from the law because of the historical/cultural aspect. In fact, Hawai'i being a state is probably the best insurance policy for kava never being banned in the unuted states. Not to mention, Hawai'i is a clear case of a place that would benefit from a resumption of more traditional kava drinking. The locals have a serious problem with METH and alcohol that causes a lot of theft and violence. Being that Hawai'i is sort of a "Polytropolis" (polynesian metropolis), it's forever tied with the modern world now, it will be hard to ever completely rid the problem. But we know that when kava drinking goes up, theft and violence goes down.
Samoa or Vanuatu would be my other most likely options if it came to it.