There are a myriad of issues we face when talking about establishing a global direct democracy. Here are a few of them:
Dual Citizenship Recognition
Not all persons in our world will at this time be legally able to register as a citizen of another country than their most local one. Even when dual citizenship is tolerated by a government, the current legal structures of our world often prevent such citizenship from being fully recognized when in the territorial boundaries of a given country. [See Multiple Citizenship]
Respect for Minority and Individual Rights
We have cultural and regional differences which exist in our world. How do we ensure that the rights of small groups or even of a single individual are respected? And at the same time, prevent those who would hold the world back from progress from thwarting it just by saying no? These are difficult questions, ones we are unlikely to answer easily. They will require us to have a vital and important discussion we must have together, ongoingly, as we move forward with the creation of The Country of Earth as a political entity.