Interesting; was thinking about this myself recently - currently based in WA - but if we opt to moving to a new country altogether I believe we would always be liable for US fed tax which makes it a little less appealing (assuming we'd end up then being 'dual-taxed').
Washington is a great place to be! If you start a digital nomad trip from there, your state taxes will be as simple as possible.
Regarding being dual-taxed, the US has dual taxation treaties with almost every country, so you can deduct the taxes you pay to another country from your US taxes. e.g. If you move to France, you'll pay taxes there, and when you file in the US you'll get credit for those taxes paid. There are numerous other complications for federal taxes as well! But you probably won't flat-out pay double.
