This brings back memories from Obama's first campaign. My parents joked that with the kind of influence the US has over us, every country should have a say in who leads them!
"Global Voting" is a poor solution to that problem, but more importantly, it is redundant. The Internet ensures that people in other countries can exert some influence over US voters. Even more importantly, migrant communities can exercise some amount of influence depending on their overall relationship with their home countries.
It's still a fun idea to think about.
